"I am not ready to withdraw from demanding the rights of the Iranian people," he said, adding that he was determined to prove electoral fraud and that those behind it were "the main factor for the recent violence and unrest and have spilled the blood of the people."

He also was quoted by his Web site as saying that the Iranian people have the right to express "their opposition to what happened in the election and after that."

The final tally was 62.6 percent of the vote for Ahmadinejad and 33.75 percent for Mousavi, a lopsided victory in a race that was perceived to be much closer.

Mousavi also defended himself and his movement, identified by the color green, against the barrage of claims on state media about foreign hands behind the unrest. "The green movement is not dependent on foreigners," he said.

Mousavi's comments came as Ahmadinejad reiterated complaints about foreign interference, singling out Obama and comparing him to former President George W. Bush, in a statement quoted by Iranian state television.

"We expect nothing from the British government and other Europeans governments, whose records and backgrounds are known to everybody and who have no dignity, but I wonder why Mr. Obama, who has come with the slogan of change, has fallen into this trap, the same route that Mr. Bush took and experienced its ending," Ahmadinejad said.

Before the election, the Obama administration had indicated it was interested in reaching out to Iran after years of a diplomatic freeze following the 1979 Islamic Revolution. Iran has given no clear signal it is interested in Obama's overture. In the wake of the vote, Obama has used increasingly harsh language to discuss Iran, saying he was "appalled" by the crackdown.

Ahmadinejad, who is to be sworn in for a second four-year term by August, warned that there would be "nothing left to talk about" if Obama kept up such a tone. "This will not have any result, except that the people will consider you similar to Bush," he said.

The comments by both presidents could complicate any attempt at a dialogue, which Washington hopes will include talks on the scope of Iran's disputed nuclear program.

Key Western powers urged Iran's leaders anew to ease up on the protesters and review the disputed election results.

"We stand beside you," German Chancellor Angela Merkel said in remarks directed to "all in Iran who seek to demonstrate peacefully."

British Foreign Secretary David Miliband, whose government expelled two Iranian diplomats earlier this week after Iran did the same to two British envoys, told the British Broadcasting Corp. there is a "crisis of credibility between the Iranian government and their own people."

And Italy said it hoped Thursday's meeting of Group of Eight foreign ministers would send a "tough" message to the regime.