"It seems that the repetition of the past U.S. administration's accusations [against Iran] would be in contrast with the slogan of change [by Obama]," Foreign Ministry spokesman Hassan Qashqavi told a news conference. "And such a thing - nuclear armament - does not exist in Iran to be inferred as a threat."
Qashqavi made the comments a day after Obama, who is seeking to engage Iran diplomatically in a sharp policy shift from George W. Bush's approach, set out his vision for ridding the world of such arms.
North Korea launched a rocket on Sunday, in defiance of warnings from the U.S. and its Asian neighbors, saying it was putting a communications satellite called Kwangmyongsong-2 into orbit. Analysust surmise that the launch was effectively a test of a ballistic missile designed to carry a warhead as far as the U.S. state of Alaska
Delivering a speech in Prague given new urgency by North Korea's rocket launch, Obama also said the United States would go ahead with plans to build a missile defence shield in Europe as long as Iran posed a threat with its nuclear activities.
Qashqavi on Monday stressed the lack of any links between Tehran's and Pyongyang's missile programs, and urged countries in that "sensitive region" to stay calm and apply their efforts to securing peace and stability.
"We believe all countries in the sensitive region of East Asia must maintain their efforts to help securing peace and stability there," he told a news confernce.
"Especially the current global economic crisis requires that differences in that sensitive region turn into peace and friendship."
Tehran insists the nature of its missile program is completely peaceful and for scientific purposes. "Our missile program is quite separate and independent from North Korea's programs ... There is no link between these two programs," Qashqavi insisted.
The West suspects Iran's nuclear program is a cover for developing bombs. Iran, the world's fourth-largest oil producer, says it is a peaceful drive to generate electricity.
Obama last month offered Iran a "new beginning" of diplomatic engagement, following three decades of hostility. Iran has responded cautiously to the overture, saying Washington must show real policy change towards Iran rather than in words.
Qashqavi said nuclear weapons had no place in Iran's defense doctrine and that the existence of such arms was a serious threat to the global community.
"We, like the rest of the world community, are awaiting a world free of nuclear arms," Qashqavi said.
"Our expectation from the U.S. and others is to take serious and practical measures towards nuclear disarmament and dismantling of weapons of mass destruction," he said.
Obama pledged on Sunday to cut the U.S. nuclear arsenal, to bring the Comprehensive Test Ban Treaty into force and to seek tough penalties for those that broke rules on non-proliferation.
He presented Iran with a "clear choice" of halting its nuclear and missile activity or facing increased isolation.
Tehran has repeatedly rejected international demands to stop its most sensitive atom work and officials say Iran will unveil "good news" when it marks its national nuclear day on Thursday.