Lt. Gen. Benny Gantz said Israel was "unequivocally" capable of launching an attack, The Jerusalem Post said.
"The Iranian challenge is a meaningful one," he said. "We must look at it strategically long-term. We will do what needs to be done, when it needs to be done."
He also said the Israeli military stands ready in the event the conflict in Syria spills over the border into Lebanon or on Israeli soil.
He remained confident, however, that such an outcome would be unlikely.
"We are ready, at any given time, and in an immediate manner, for a war with Syria, both on the defense and on the offense," he said. "I don't see it happening tomorrow morning, but despite that we are ready."