Addressing a packed hall, Lewis spoke after a screening of the film 'Obsession: Radical Islam's War Against the West'.
"Ahmadinejad and his group clearly believe, and I don't doubt the sincerity of their belief, that we are now entering an apocalyptic age, which will result in the triumph of their messianic figure," Lewis said, referring to the twelfth Imam, Mahdi.
"Muslims, like Jews, believe that there are things you can do to hasten the messiah. M.A.D doesn't work with these people."
Lewis added that the threat of many Iranians perishing in a war did not deter the Iranian leadership, which believes "it would be doing them a favor, by giving them a free pass to heaven."
"Iran is a mortal threat, and one also has to take account of the apocalyptic mood of Ahmadinejad and his circle. Islam, like Judaism and Christianity, has an end of time scenario," the scholar said.
"There is only solution to the Iranian threat, and that can only come from the Iranian people," Lewis said.
'Holy war is part of Islam'
During his lecture, Lewis said Islam was neither a religion of complete peace nor a religion of war symbolized by a horseman riding with a Koran and a sword.
"The truth is somewhere in the middle," he said. "Holy war is part of the religion, and part of holy law… according to which it must be declared, and a warning issued. Attacking non-combatants is forbidden," Lewis said.
Addressing suicide terrorism, the historian added that "suicide is expressly forbidden by Islamic holy law," noting that the act carried the punishment of "forfeiting heaven and going straight to hell."
Lewis also said his acclaimed book, Semites and anti-Semites, which addresses Arab anti-Semitism, will be published in Arabic in Cairo.