TEHRAN, Iran — Iranian President Mahmoud Ahmadinejad on Tuesday sought to put the turmoil over the disputed presidential elections behind him and declared on national television that the contests were clean, fair and were the start of a new era.

His speech came as the country's top three reformist leaders sought to rekindle their opposition movement, demanding that ruling clerics end the heavy "security atmosphere" imposed after the elections and free those detained in the unrest, according to an opposition Web site.

It was Ahmadinejad's first national speech since the supreme leader declared the election results valid despite outcry from the other candidates and weeks of street protests that the results were fraudulent.

"This is a new beginning for Iran ... we have entered a new era," the president said, explaining that the 85 percent turnout and overwhelming win had given his government a new legitimacy.

"The election ... was completely clean and healthy. In the re-count, no fault was discovered. The whole nation understood this," he said. "This election has doubled the dignity of the Iranian nation."

During the half hour speech, Iranians in many parts of the city could be heard shouting from their rooftops, "death to the dictator" and "God is great" — actions that have become a symbol of defiance since the elections.

Meanwhile, opposition leader Mir Hossein Mousavi, who claims to have won the June 12 election, is struggling for a way to channel the widespread discontent which erupted into huge street protests over alleged fraud in the vote but which has since been shattered by the harsh crackdown by police, Revolutionary Guards and Basij militia.

Mousavi hinted on Monday that he may move away from the tactic of protests and create a political party to work in what he called "a legal framework." Late Monday, he met with the top other top stars of the reform movement — former president Mohammad Khatami and Mahdi Karroubi, another election candidate — in a show of unity.

The three warned Iran's clerical leadership that if the security crackdown continues, it "will only lead to radicalization of political activities," Mousavi's Web site reported on Tuesday.

But it is not clear how much margin the opposition will have for political action. Many of the top reform figures — including Khatami's former vice president and one-time members of his Cabinet — are in detention and could face charges of fomenting riots. Earlier this week, the head of the Revolutionary Guards warned that the elite force would take a major role in defending the country's system of clerical rule.