"The (UN) resolution was born dead and even if they issue 10 more of such resolutions it will not affect Iran's economy and policies," Ahmadinejad said in a speech to parliament broadcast live on state television.
The president has faced increasing public criticism in Iran since the resolution was passed and after his supporters were trounced in local polls in December. Critics say his anti-Western speeches have added to tensions with the West.
"They want to say, through a psychological war, that the resolution has been very effective ... Falsely, they want to say that Iran has paid a price," the president said. "We have become a nuclear country today without promising anything to the major powers and this is a great victory that belongs to the people and the parliament," he added.
Although the resolution targeted sensitive aspects of Iran's nuclear programme, businesses say investors are being scared off because of the fear of escalation and already meager investment flows are drying up.
US Secretary of State Condoleezza Rice told Der Spiegel magazine that companies should beware of doing business with Iran and think about the possibility of more sanctions.
"I think people ought to think about the risk of further sanctions. The United States is clearly sanctioning Iranian banks and our laws are very tough on those who deal with banks that we have sanctioned," Rice said according to an English transcript of the interview.
Iran, the world's fourth largest oil exporter, is enjoying windfall oil revenues but its efforts to prime the economy with petrodollars is fuelling inflation and failing to shrink the country's queues of jobless people.