"We will submit our formal complaint against this kind of threats to the United Nations," Iranian Foreign Ministry Spokesman Ramin Mehman-Parast was quoted by Fars news agency as saying.
The spokesman said that Obama's threat to use nuclear weapons against Iran was a "threat to global peace and security."
About 222 lawmakers of Iran's 290-seat parliament called on the government to file the complaint.
On Tuesday, Apr 6, Obama had said that his administration would only use atomic weapons in "extreme circumstances" and would not attack non-nuclear states that complied with the Nuclear Non-Proliferation Treaty.
But Iran and North Korea were pointedly singled out as exceptions because Washington accuses them of not cooperating with the international community on non-proliferation standards.
Obama had said, "Outright that the loophole would apply to outliers like Iran and North Korea that the US believes are developing nuclear weapons."
The US and some of its allies accuse Iran of seeking to develop nuclear weapons, but Tehran has denied the charges, saying its nuclear programme is peaceful.