“If the U.S. and its allies think they could hold the stick of sanctions and then sit and negotiate with us, they are seriously mistaken,” he told a news conference, according to Iran’s state-run Press TV satellite broadcaster. European and American officials say the vote on sanctions could come as early as Wednesday.

Image Prime Minister Tayyip Erdogan of Turkey, left, with Prime Minister Vladimir V. Putin of Russia on Tuesday in Istanbul. Credit... Osman Orsal/Reuters

Mr. Ahmadinejad said Iran would not repeat its recent offer to send part of its stockpile out of Iran for enrichment. The accord, supported by Brazil and Turkey, was designed to break the deadlock over its nuclear program, according to Iran.

“The Tehran declaration provided an opportunity for the United States government and its allies. We had hoped and we are still hopeful that they use the opportunity well,” Mr. Ahmadinejad said. “I must say opportunities like this will not be repeated again.”

He added: “We were thinking that the United States President Barack Obama would make certain changes in the United States policies. We don’t say that we are hopeless. We hope that he can actually get over the present conditions in the time that remains. We are ready for dialogue within the frame of justice and respect.”

The United States contends Iran is trying to develop nuclear weapons, while Iran argues its nuclear program is peaceful. The deal brokered by Turkey and Brazil last month was based on parts of a previous United Nations-backed offer for Tehran to give up 1,200 kilograms of low enriched uranium in exchange for special fuel for a medical research reactor.