Iran's president expressed openness for talks with the United States but again dismissed demands to halt nuclear work in an interview with Germany's Der Spiegel news magazine.
Mahmoud Ahmadinejad also called for "fundamental changes" in Washington's policies, echoing comments by Supreme Leader Ayatollah Ali Khamenei and other senior Iranian officials.
"If the behavior of the United States changes, we can expect to see important progress," he said in the interview posted on Der Spiegel's website, referring to decades of mistrust between Tehran and Washington.
The administration of President Barack Obama has offered a "new beginning" of diplomatic engagement if the Islamic Republic "unclenches its fist."
Breaking with past US policy of shunning direct talks with Tehran, Washington last week said it would join discussions with Iran on its disputed nuclear program from now on.
Der Spiegel said the interview was conducted about a week ago, before the United States and five other world powers said they would invite Iran to a meeting on the nuclear issue.
An aide to Mr Ahmadinejad has said Iran would review the offer.
Iran has reacted cautiously to Washington's overtures, saying it wants to see a real shift in US policy from the Bush administration, which spearheaded a drive to isolate Tehran over its refusal to stop enriching uranium.
"We support talks on the basis of fairness and respect. That has always been our position. We are waiting for Obama to announce his plans, so that we can analyze them," Ahmadinejad said in an English translation of the interview.
"We speak very respectfully of Barack Obama. But we are realists. We want to see real changes," he said. "We feel that Obama must now follow his words with action."
While seeking to engage Iran, Obama's administration has also warned of tougher sanctions if it continues to defy United Nations demands to halt sensitive nuclear work.
Mr Ahmadinejad made clear once again Iran would not bow to such pressure and suspend uranium enrichment, which can have both civilian and military uses.
"These discussions are old. The time for this is over," he said.
Turning to neighboring Afghanistan, he said Tehran was interested in "helping correct a faulty" US policy there.
Mr Obama announced his strategy for stabilizing Afghanistan and Pakistan on March 27, pledging additional troops to train Afghan forces and more civilians to spur Afghanistan's development. The United States now has about 38,000 troops in Afghanistan.
Iran has often called on US forces to leave the region, saying their presence is making the security situation worse.