Peres, in an interview with Kol Hai Radio, urged Iranian President Mahmoud Admadinejad to enter into talks proposed by U.S. President Barack Obama. If Admadinejad ultimately fails to soften his nuclear stance, "we'll strike him," Peres said Sunday.
Peres declined to go into detail, saying only that a strike against Iran could not happen without support from the United States.
"We certainly cannot go it alone without the U.S., and we definitely can't go against the U.S. This would be unnecessary," Peres said.
Peres said Admadinejad's power suffered a blow last week when Egyptian forces arrested members of a Hezbollah terror cell, The Jerusalem Post reported Sunday.
"Admadinejad recruits forces against us, but there are also forces against him," Peres said. "What happened in Egypt created a fierce opposition and we must unify all his opponents -- the Sunnis and the Europeans, as well as those afraid of nuclear weapons and terror."