Saying it was time to lead a "diplomatic process," Barak Wednesday said if a permanent agreement couldn't be reached, "we must consider an interim arrangement or even a unilateral move," Haaretz reported.
"We are on borrowed time. We will reach a wall, and we'll pay the price. People who are now in a coma will then ask how we didn't see [this coming]," he said during a speech at Tel Aviv University's Institution for National Security Studies.
Turning to Iran's nuclear program, Barak said it was "impossible to sleep soundly while the Iranians are moving systematically toward a point where Israel won't be able to do anything."
Barak dismissed criticism that Israeli leaders wanted war, but said Israel couldn't just wait for the Iranians to achieve nuclear capability, Haaretz said.
"The difficulty of the international community in taking action, even in a clear case like Syria, must tell us something about other areas as well," he said.
Barak criticized Syrian President Bashar Assad, calling last week's massacre of more than 100 people in Houla "a new record in ruthless murder by the Assad regime."
"The world must act, and not just talk. These are crimes against humanity," Barak said.