It was the first public comment by the Iranian leader on the two-page document since its existence was revealed by The Times of London last week.
According to the newspaper, the document shows Iran has been secretly working on testing a neutron initiator -- the part of a nuclear bomb that triggers an explosion. The technology has no use aside from detonating a nuclear weapon.
Critics of the Iranian regime have seized on the revelation as a smoking gun -- one of the strongest indicators yet of a continuing nuclear weapons program in Iran.
But when asked point-blank whether Iran had been testing a neutron initiator, the Iranian president was dismissive.
"I think that some of the claims about our nuclear issue have turned into a repetitive and tasteless joke," Ahmadinejad said in the interview.
Asked about Ahmadinejad's allegation that the U.S. government fabricated documents, White House Senior Adviser David Axelrod said: "Of course that's nonsense." Read more at ABC News