Iranian President Mahmoud Ahmadinejad says his re-election was "real and free" and cannot be questioned — but that isn't stopping his campaign rival from appealing the results.
Reformist Mir Hossein Mousavi accused the government of voter fraud and many of his supporters have clashed with police in Tehran's streets.
"Today, I have submitted my official formal request to the council to cancel the election result," Mousavi said in a statement. "I urge you Iranian nation to continue your nationwide protests in a peaceful and legal way."
Protesters set fires and smashed store windows Sunday in a second day of violence as groups challenging Ahmadinejad's re-election tried to keep pressure on authorities. Anti-riot police lashed back and the regime blocked Internet sites used to rally the pro-reform campaign.
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 earlier released a statement saying that 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.
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.
On Sunday in the first news conference since the election results were announced, several Iranian journalists first congratulated Ahmadinejad for his victory. When asked about the allegations of voting irregularities, the hard-line president brushed the claims off, calling them unimportant.
"Some believed they would win, and then they got angry. It has no legal credibility. It is like the passions after a football match. It is not important from my point of view," Ahmadinejad said.
"The margin between my votes and the others is too much and no one can question it."
Ahmadinejad accused foreign media of launching a "psychological war against" against the country.
"Who dares to attack Iran? Who even dares to think about it?" Reuters quoted Ahmadinejad at the press conference.
Ahmadinejad's unexpectedly overwhelming victory and its violent aftermath raised fresh questions about how Iran will respond to U.S. President Barack Obama's diplomatic overtures.
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 bit to undercut liberal voices.
Web sites linked to reformists' new hero Mir Hossein Mousavi, who declared himself the true winner of Friday's presidential race and urged backers to resist the government, were down. Social networking sites including Facebook and Twitter were also not working.
The U.S. has refused to accept Ahmadinejad's claim of a landslide re-election victory said it was looking into allegations of election fraud. There are no independent election monitors in Iran.
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.
U.S. Secretary of State Hillary Rodham Clinton said Saturday she hoped the outcome reflects the "genuine will and desire" of Iranian voters.
The European Union also said it was "concerned about alleged irregularities" during Friday's vote.
Past Iranian elections were considered generally fair. In 2005, when Ahmadinejad was first elected, the losing candidates claimed irregularities at the polls, but the charges were never investigated.
Mousavi called on his backers to avoid violence, but he is still talking tough about pressing his claims of election fraud. He charges the polls closed early but has not fully outlined all of his fraud allegations.
The Associated Press contributed to this report.