President Mahmoud Ahmadinejad said on Tuesday Iran is prepared to talk to the United States in an atmosphere of equality and mutual respect after three decades of severed ties.

"The Iranian nation will welcome true changes and is ready for dialogue in a climate of equality and mutual respect," he told a huge rally at Tehran''s Azadi (Freedom) Square in a speech marking 30 years since the Islamic revolution.

"It is clear that the change must be fundamental and not tactical ... The era of bullying is over and the era of dialogue has started."

On Monday, US President Barack Obama renewed his call for direct talks, saying he hoped to create the conditions for face-to-face dialogue in the months ahead.

Reacting to Ahmadinejad''s remarks, US Secretary of State Hillary Clinton said she hoped the two countries might "develop a better understanding of one another" that produces positive results for Iran''s people, but renewed US opposition to Tehran''s nuclear ambitions.

"We still persist in our view that Iran should not obtain a nuclear weapon," she said in Washington.

Tens of thousands of Iranians chanting anti-US slogans still took to the streets on Tuesday at a time of continuing tense relations.

Demonstrators bore placards reading "30 years of freedom, 30 years of pride," "Death to America" and "Death to Israel."