Ahmadinejad dismissed Tehran’s worst unrest in a decade as “not important,” comparing it to passions after a football match. He insisted Friday’s vote was “real and free” and the results showing his landslide victory were fair and legitimate. Along Tehran’s Vali Asr street — where activists supporting rival candidate Mir Hossein Mousavi held a huge pre-election rally last week — tens of thousands marched in support of Ahmadinejad, waving Iranian flags and shouting his name.

Mousavi sent a letter to the Guardian Council — a powerful clerical group — calling for the election to be canceled. He has claimed that he was the real winner.

“Fraud is evident and review and nullification is requested,” said the letter posted on Mousavi’s Web site. Mousavi also met Iran’s supreme leader Ayatollah Ali Khamenei to discuss his fraud allegations. Shahab Tabatabaei, a prominent activist in Mousavi’s pro-reform camp, said Mousavi called on Khamenei to order cancellation of the election results.

Mousavi earlier released a statement said canceling the election is the only way to restore public trust. He urged supporters to continue their “civil and lawful” opposition to the results and advised police to stop violence against protesters.

The violence has pushed Iran’s Islamic establishment to respond with sweeping measures. They have deployed anti-riot squads around the capital and cut mobile phone messaging and Internet sites used by Mousavi’s campaign.

There is little chance the youth-driven movement could immediately threaten the pillars of power in Iran — the ruling clerics and the vast network of military and intelligence forces at their command. But their discontent raises the possibility that a sustained and growing backlash could complicate Iran’s policies at a pivotal time.

President Barack Obama has offered to open dialogue after a nearly 30-year diplomatic freeze. Iran also is under growing pressure to make concessions on its nuclear program or face possible more international sanctions.

Vice President Joe Biden said Sunday he has doubts about whether the election was free and fair. He said the U.S. and other countries need more time to analyze the results before making a better judgment.

In Paris, French Foreign Minister Bernard Kouchner said his country is “very worried” about the situation in Iran and criticized authorities’ “somewhat brutal reaction” to the protests.

Mahdi Karroubi, a moderate former parliament speaker who also ran in the election, also challenged the election result.

“The results for the election are illegitimate and the government lacks national dignity and social competence,” he said in a statement. “So I do not recognize Mr. Mahmoud Ahmadinejad as president of Iran.”

In a second day of clashes, scores of young people shouted “Death to the dictator!” and broke the windows of city buses on several streets in central Tehran. They burned banks and set first to trash bins and piles of tires, using them as flaming barricades to block police.

Riot police beat some of the protesters with batons while dozens of others holding shields and motorcycles stood guard nearby. Shops, government offices and businesses closed early as tension mounted.

Ahmadinejad called the level of violence “not important from my point of view,” speaking at a news conference.

“Some believed they would win, and then they got angry,” he said. “It has no legal credibility. It is like the passions after a football match. … The margin between my votes and the others is too much and no one can question it.”

“In Iran, the election was a real and free one,” said Ahmadinejad. “The election will improve the nation’s power and its future,” he told a packed room of Iranian and foreign media.

About a mile away from Ahmadinejad’s news conference, young Iranians set trash bins, banks and tires on fire as riot police beat them back with batons.

Ahmadinejad accused foreign media of launching a “psychological war” against the country, repeating a charge he also made on Saturday.

Iranian authorities have asked some foreign journalists — in Iran to cover the elections — to prepare to leave.

Nabil Khatib, executive news editor for Dubai-based news network Al Arabiya, said the station’s correspondent in Tehran was given a verbal order Sunday from Iranian authorities that the office will be closed for one week. No reason was given for the order, but the station was warned several times Saturday that they need to be careful in reporting “chaos” accurately.

Iran restored cell phone service that had been down in the capital since Saturday. But Iranians could not send text messages from their phones, and the government increased its Internet filtering in an apparent attempt to undercut liberal voices. Social networking sites including Facebook and Twitter were also not working.

The restrictions were likely intended to prevent Mousavi’s supporters from organizing large-scale protests. But smaller groups assembled around the city. About 300 Mousavi supporters gathered outside Sharif University, chanting “Where are our votes?”

About a dozen riot police used batons to disperse about 50 Mousavi supporters standing outside his campaign quarters.

On Saturday, Mousavi, a 67-year-old former prime minister, released a Web message saying he would not “surrender to this manipulation.” Authorities responded with targeted detentions, apparently designed to rattle the leadership of Mousavi’s “green” movement — the trademark color of his campaign.

The detentions include the brother of former reformist President Mohammad Khatami and two top organizers of Iran’s largest reformist party, the Islamic Iran Participation Front: the party’s secretary-general and the head of Mousavi’s youth cyber campaign. Mohammad Reza Khatami and the two party activists were released Sunday.

Several others linked to Mousavi’s campaign remained in custody, but the full extent of the arrests were not known.

Tehran deputy prosecutor, Mahmoud Slarkia, told the semi-official ISNA news agency that fewer than 10 people were arrested on the charge of “disturbing public opinion” through their “false reports” on Web sites after the election. He did not mention any names.

Iran’s deputy police chief, Ahmad Reza Radan, told the official Islamic Republic News Agency that about 170 people have been arrested for their involvement in Saturday’s protests. He said 10 of those arrested were “main planners” and 50 were “rioters.” The others were arrested for being at the site of the clashes, he said. Some of the detained were active in Mousavi’s campaign headquarters or had relations with foreign media, he said.

“Police will not allow protesters to disturb the peace and calmness of the people under the influence of foreign media,” Radan said on state television, which showed footage of the protests for the first time Sunday.

Mousavi’s newspaper, Kalemeh Sabz, or the Green Word, did not appear on newsstands Sunday. An editor, who spoke on condition of anonymity because of the sensitivity of the situation, said the paper never left the printing house because authorities were upset with Mousavi’s statements.

The paper’s Web site reported that more than 10 million votes in Friday’s election were missing national identification numbers similar to U.S. Social Security numbers, which make the votes “untraceable.” It did not say how it knew that information.

“Don’t worry about freedom in Iran,” Ahmadinejad said at his news conference after a question about the disputed election. “Newspapers come and go and reappear. Don’t worry about it.”

Iran’s supreme leader, Ayatollah Ali Khamenei, has closed the door for a possible compromise. He could have used his near-limitless powers to intervene in the election dispute. But, in a message on state TV on Saturday, he urged the nation to unite behind Ahmadinejad, calling the result a “divine assessment.”