Vahid Salemi / AP

Iranian President Mahmoud Ahmadinejad, center, waves to well wishers from his car during an annual rally commemorating the anniversary of the 1979 Islamic revolution on Sunday.

DUBAI - Iranian President Mahmoud Ahmadinejad said on Sunday Tehran would not negotiate about its disputed nuclear program under pressure, but would talk to its adversaries if they stopped "pointing the gun.'

In a speech to mark the 34th anniversary of the Islamic revolution, Ahmadinejad struck a more conciliatory tone than Supreme Leader Ayatollah Ali Khamenei, who on February 7 rebuffed a U.S. call for direct negotiations on disputes between the two countries. 

Ahmadinejad does not have the authority to authorize negotiations over the nuclear program, which lies with Khamenei. 

"You cannot point a gun at the Iranian nation and then expect them to have negotiations with you," Ahmadinejad said, speaking to a crowd gathered in Tehran's Azadi (Freedom) Square. 

His speech, which partly dealt with Iran's policy towards its 'enemies', was carried live on Iranian state television. 

"Talks should not be used as a lever to impose one's opinions.... If you stop pointing the gun at the Iranian nation, I will negotiate (with you) myself," he added. 

The U.S. and some of its allies suspect Iran may be trying to develop atomic weapons capability under the cover of a civilian nuclear energy program, a charge Iran has denied. 

Many believe no nuclear deal is possible without a U.S.-Iranian thaw, requiring direct talks addressing myriad sources of mutual mistrust and hostility lingering since Iran's 1979 Islamic Revolution and the hostage crisis at the U.S. embassy in Tehran. 

On the nuclear dispute, Iran has agreed to a new round of talks with world powers in Kazakhstan on February 26. 

Related: Iran's supreme leader rejects Joe Biden's offer of direct talks

Tehran is seeking the lifting of sanctions that have slashed oil exports and helped reduce the value of the Iranian rial by about half in the last year, contributing to higher inflation and weakened purchasing power for ordinary Iranians. 

Slideshow: Everyday life in Iran

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Iranians bearing banners saying "Down With U.S.A." and "We are standing until the end" gathered at state-organized mass demonstrations in the capital Tehran and other major cities to mark the anniversary of the ousting of a Western-friendly monarchy in favor of clerical leadership. 

Ahmadinejad did not address the specifics of Iran's nuclear program, or of the planned talks, in his speech on Sunday. He said that Iran would counter the sanctions by increasing its non-oil exports and weaning itself off crude revenues. 

"Today the enemies are trying their utmost to put pressure on the Iranian nation to stop its progress but they will not succeed," he said. 

Last week, the U.S. implemented a measure meant to "lock up" Iranian oil revenues by requiring them to be credited to accounts in countries that buy Iranian crude. 

Supreme leader Khamenei on Thursday slapped down an offer of direct negotiations with the United States, saying negotiations and pressure were incompatible. 

Khamenei was believed to have been replying to remarks by Vice President Joe Biden, who said in a speech in Germany on February 2 that the United States was ready to hold direct talks with Iran if it was serious about negotiations. 

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MUNICH - The United States is ready for direct talks with Iran if it is serious about negotiations, Vice President Joe Biden said late Saturday, backing bilateral contact many see as crucial to easing a dispute over Tehran's nuclear program.

Speaking at a security conference in Munich, Biden said Iran - which says it is enriching uranium for peaceful energy only - now faced "the most robust sanctions in history" meant to ensure it does not develop nuclear weapons.

"But we have also made clear that Iran's leaders need not sentence their people to economic deprivation and international isolation," Biden said. "There is still time, there is still space for diplomacy backed by pressure to succeed. The ball is in the government of Iran's court."

To date, fitful talks on Iran's nuclear program have been between Tehran and the EU's top diplomat representing six world powers including Washington. But analysts have suggested that with his re-election behind him, President Barack Obama might have more leeway to take on direct negotiations with Iran.

That makes the year ahead critical for chances of overcoming a stand-off which, if left to fester further, could see Iran approach nuclear weapons capability, possibly provoking military action by Israel that could inflame the Middle East.

Progress on Iran would also help ease regional tensions as the United States prepares to pull most combat troops out of Iran's neighbor Afghanistan by the end of 2014.

Asked whether Washington might consider direct talks with Iran to smooth the process, Biden said, "When the Iranian leadership, Supreme Leader (Ayatollah Ali Khamenei), is serious.

"We have made it clear at the outset that we would be prepared to meet bilaterally with the Iranian leadership, we would not make it a secret that we were doing that, we would let our partners know if that occasion presented itself.

"That offer stands, but it must be real and tangible and there has to be an agenda that they are prepared to speak to. We are not just prepared to do it for the exercise."

Negotiations with Iran have so far been overseen by European Union foreign policy chief Catherine Ashton on behalf of France, Britain, Germany, China, Russia and the United States. But they have made scant headway, raising fears Iran is simply playing for time while it develops nuclear know-how.

Many believe no deal is possible without a U.S.-Iranian thaw, requiring direct talks addressing myriad sources of mutual mistrust and hostility lingering since Iran's 1979 Islamic Revolution and the hostage crisis at the U.S. embassy in Tehran.

Iran has avoided direct, public talks with the United States, though some suggest Tehran would eventually welcome an opportunity to end its international isolation.

Speaking at a news conference in Munich, Republican Senator John McCain said he would have no objection to direct talks but questioned how much these would achieve if fundamental questions over Iran's nuclear program remained unresolved.

"I don't know when we will have direct talks between the United States and Iran. That is a subject for the president of the United States. I don't think anyone here objects to that," he said. But he added, "to have grounds for optimism, I think, would be a mistake."

Israel, which describes the prospect of Iran being able to weaponize enriched uranium as an existential threat, has made clear it would be ready to bomb the nuclear sites of its arch-enemy to prevent that outcome. The United States has also said it would not rule out the use of military force. 

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