Ramin Mehmanparast, a spokesman for the Iranian Foreign Ministry, said the United States was among the countries violating the Nuclear Non-Proliferation Treaty.
"There are certain countries which are threatening to use nuclear weapons if necessary," he was quoted by Iran's Press TV as saying from Croatia. "The U.S. and France are among such countries."
U.S. allies have said they weren't taking any options off the table to prevent Iran from obtaining a nuclear weapon.
Multilateral talks in Istanbul over Iran's nuclear ambitions were said to be productive, however. Tehran said another round of negotiations was scheduled for May 23 in Baghdad.
Iran is suspected of pursuing the technology needed to manufacture a nuclear weapon, an allegation the Iranian government denies.
"All nuclear activities of Iran are peaceful and all our sites are under the surveillance of the International Atomic Energy Agency's cameras," Mehmanparast said.
The IAEA had said there may be some military dimensions to certain aspects of Iran's nuclear program.