Ahmadinejad, speaking to reporters on the sidelines of a security summit, also said new sanctions against his country would be a mistake and that U.S. President Barack Obama stands to lose unless he changes his policies toward Iran. He did not elaborate.
"The meeting in Tehran created an opportunity for the U.S. administration and for its allies and we still hope that they will be able to use this opportunity," Ahmadinejad said of the nuclear swap deal that was reached in Tehran and that aims to address international concerns over Iran's nuclear program. "We say that this opportunity will not be repeated."
"Unless their policies change, Obama will be the first to lose, and then the U.S. government," the Iranian president said.
Ahmadinejad was speaking days before the U.N. Security Council is expected to vote to punish Tehran for its refusal to heed demands to curb its nuclear program.
The head of the International Atomic Energy Agency on Monday singled out Iran for the first time as a "special case" because of suspicions it may be trying to make nuclear weapons. A senior Iranian envoy said Israel was the true threat to Mideast peace.
Under the nuclear swap deal, Iran would deposit 1,200 kilograms of lightly enriched uranium in Turkey. In exchange, Iran would get 120 kilograms of nuclear reactor fuel.
U.S. officials have criticized the agreement, in part because it does not stop Iran from continuing to enrich uranium. The U.S. also says the deal is a ploy by Iran to delay new international sanctions.
Turkey and Brazil, both non-permanent members of the U.N. Security Council, are now pressing for an open "political debate" on the broader Iranian nuclear issue before a vote on new sanctions.
"We say: peaceful nuclear for all, nuclear bombs for none," Ahmadinejad said.