Foreign Ministry spokesman Mohammad Ali Hosseini said at his weekly briefing that Washington and the other Western powers won't succeed in their efforts to halt Iran's nuclear program.
"They are looking for excuses," he said. "This will not bear fruit and will mostly work against them and we will continue our constructive cooperation with the agency."
Hosseini noted that the International Atomic Energy Agency had confirmed that Iran wasn't seeking nuclear weapons, a fact supported by the U.S.'s own national intelligence estimate released last month, though this "has not led to any change in the attitudes of some of these (Western) countries."
Washington is pursuing fresh U.N. sanctions at a meeting of the five permanent United Nations Security Council members, including China, and Germany on Tuesday in Berlin. The U.S. is also considering imposing more penalties of its own to step up pressure on Tehran to its uranium enrichment activities that could lead to the development of a nuclear weapon.
Earlier in January, IAEA director Mohammed Elbaradei, visited Tehran and Iran agreed to answer all questions over its nuclear activities in the next few weeks.
Tehran says it has never worked on developing atomic weapons and wants to enrich uranium only to produce fuel for reactors to generate electricity. The U.S. and its allies say that even if Iran no longer has an active weapons program, it could easily resume such work unless strong international oversight is put in place.
In November, an IAEA report said Iran had been generally truthful about key aspects of its nuclear history, but warned that its knowledge of Tehran's present atomic work was shrinking.
While Iran has responded to many IAEA questions about past nuclear activities, some issues still remain unresolved.