Addressing a large gathering in the central city of Isfahan where Iran has a uranium conversion facility, Ahmadinejad referred to US President Barack Obama as saying Iran has no right to have a atomic bomb.

"Recently, you (Obama) said that Iran can have nuclear technology for peaceful purpose, but does not have the right to have a bomb," Ahmadinejad said.

"I am telling you that the Iranian nation was never seeking a bomb as the era of bombs and armies is over," he said as the crowd cheered with chants of "Death to America!."

Since taking office, Obama has made a series of diplomatic overtures towards Iran and last month on the Persian New Year, in a message to the Iranian people, he called for a "new beginning" in ties between Washington and Tehran.

On Monday, however, he warned that Iran had to make a choice between having a nuclear weapon and building a better future for its people.

"I have made it clear to the people and leaders of the Islamic republic that the United States seeks engagement based upon mutual interests and mutual respect," Obama said in address to the Turkish parliament.

"Now, Iran's leaders must choose whether they will try to build a weapon or build a better future for their people."

Ahmadinejad said Iran was still waiting for "fundamental and real changes" from Obama and the United States, with whom Tehran has had no diplomatic ties for three decades.

"If you are talking of change ... bismillah (In the name of God) ... change your method, your vocabulory and the path towards Iran," the Iranian leader said.

"You have extended your hand to us. If you are sincere in it, we welcome it, but if not, then our reply will be same as the one we gave to Mr (George W.) Bush."

Relations between Washington and the Islamic republic deteriorated sharply under Bush who refused to talk to Tehran until it suspends its uranium enrichment programme.

Global powers led by the United States suspect that Iran's nuclear programme is aimed at developing atomic weapons, a charge vehemently denied by Tehran.

On Thursday, Iran is to mark its national atomic energy day in Isfahan where Ahmadinejad is expected to make a key announcement.

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