"Do you think you are dealing with a 4-year-old child to whom you can give some walnuts and chocolates and get gold from him?" he told a crowd in the central Iranian city of Arak, Reuters reported.
Arak is the site of a heavy water reactor opposed by the United States because the plutonium it produces could be used to make weapons.
France, Germany and Britain plan to offer the Islamic country a light water reactor to replace it as part of a package of incentives aimed at convincing the nation to end its nuclear program.
Developing weapons from light water reactors is significantly harder than creating them from heavy water reactors.
Although Iran insists it is enriching and reprocessing uranium for peaceful energy purposes, a right under the nuclear Non-Proliferation Treaty, the EU and United States fear the existence of a clandestine military program.
In a nationally televised speech marked by shouts from the crowd of "we love you, Ahmadinejad," the president warned the Europeans not to follow the United States in pressuring Iran. He said such pressure could lead to reactionary measures.
"Don't force governments and nations which are signatories to the nuclear Non-Proliferation Treaty to pull out of it," he said, according to the Associated Press.
Ahmadinejad said Iran would not accept any freeze of its program.
"We trusted you three years ago and accepted suspension but unfortunately this proved to be a bitter experience in Iranian history. We will not be bitten by the same snake twice," he said.
Iran suspended its nuclear fuel activities in 2003 as part of diplomatic talks pushed by the European Union, but resumed its program in 2005 when talks failed.
With its program now being considered by the U.N. Security Council, the country could face economic sanctions. The United States is pushing for a resolution that forces Iran to end its program, a resolution that could be militarily enforceable, the Associated Press reported.
Russia and China, which have economic ties to Iran, oppose sanctions and military action and favor continued diplomacy.
On Tuesday, Russian Foreign Minister Sergey Lavrov reiterated a statement that Moscow and Beijing would not vote in favor of using force to resolve the impasse, Reuters reported.
A meeting of the five permanent members of the Security Council scheduled for Friday to discuss how tough the Security Council should get if Iran refuses to end its program after incentives have been offered, has been rescheduled for Tuesday, European diplomats told the AP.