Speaking in the southwestern provincial capital of Ahvaz, Ahmadinejad said the Security Council's resolution last month was invalid and had left the world body's reputation in tatters.
The council voted unanimously to bar all countries from selling materials and technology to Iran that could contribute to its nuclear and missile programs. It also froze the assets of 10 Iranian companies and 12 individuals related to those programs.
"Let the world know that from the Iranian nation's point of view, this resolution has no validity," Ahmadinejad said.
He said the United States was the main power behind the resolution, and warned Washington: "I want you to know that the Iranian nation has humiliated you many times, and it will humiliate you in future."
The U.S. has led the drive to stop Iran from enriching uranium — a process that produces the material for either nuclear reactors or bombs. Iran denies that it seeks to build atomic weapons, saying its nuclear program is limited to the generation of electricity.
Ahmadinejad said the sanctions were not important but were part of a campaign of psychological warfare against Iran that was designed to provoke dissent within the country.
Recalling the West's support for Iraq, then ruled by Saddam Hussein, during its eight-year war with Iran in the 1980s, he said: "If all the powers that supported Saddam in his war against Iran were to regroup and confront Iran again, Iranians would deliver a historic slap in their face."
Ahmadinejad said Iran had done everything it could to prove that its nuclear program is peaceful, but the West — in the name of opposing nuclear weapons — was trying to thwart Iran's development.
"We have tried all legal, wise and logical ways to convince these corrupt and selfish powers," he said.
While Ahmadinejad has repeatedly attacked the Security Council resolution, he has avoided any public comment on the results of Dec. 15 municipal elections, in which his political allies were heavily defeated.
The polls were seen as an electoral test of Ahmadinejad's presidency, and the success of his opponents suggested that voters want him to pay more attention to domestic issues rather than foreign policy.
Some people in the crowd in Ahvaz on Tuesday tried to remind the president of the need to address domestic problems. State television showed a placard carried by one spectator that read: "Inflation, unemployment, insecurity, drug addiction have desiccated the tree of the revolution."
Inflation is officially at 12 percent but thought to be much higher, and an estimated 3 million people are unemployed.