Iran was open to resuming talks by late August or early September with permanent members of the UN Security Council and Germany, Ahmadinejad was quoted as telling Japan's Yomiuri Shimbun newspaper in an interview.
Supreme leader Ayatollah Ali Khamenei said on Wednesday Iran would not conduct talks with the United States about its nuclear program unless sanctions and military threats were lifted.
Iran last met the US, UK, China, France, Germany and Russia in October, when they discussed Iran sending low-enriched uranium abroad in exchange for fuel for a Tehran reactor that makes medical isotopes.
"We promise to stop enriching uranium to 20 percent purity if we are ensured fuel supply," Ahmadinejad was quoted as saying in the interview, published in Japanese.
Iran said in February it had started enriching uranium to the 20 percent level, something analysts said meant it could advance to weapons-grade level within months should it wish to. Iran says its work is for peaceful purposes only.
But the Yomiuri said Ahmadinejad rejected calls for Iran to stop all of its uranium enrichment, including production of low-enriched uranium.
"We have a right to enrich uranium," he was quoted as saying. "We have never initiated war or wanted nuclear bombs." On sanctions from the UN Security Council, Ahmadinejad said the measures would not hurt the Iranian economy.
The UN Security Council imposed a fourth round of sanctions on Iran in June. Iran has also been hit by tougher measures by the United States, the European Union and several other countries concerned that its nuclear programs could be a cover for acquiring a bomb.
"Sanctions will not have an effect on Iran and failure of the resolution will become clear in six to seven months," Ahmadinejad was quoted as saying.
