"A nuclear Iran is a threat to the whole world, not just to Israel ... Other major powers in the Middle East will have to try to reach nuclear capability, probably Saudi Arabia, probably Turkey, probably even Egypt," Barak told reporters in Tokyo.
"We have to accelerate the pace of imposing sanctions and make them crippling and consequential to such an extent that the leadership ... will be compelled to sit down and ... ask themselves 'are we ready to pay the price of isolation from most, if not all, of the world?'" he said.
Barak said despite Western sanctions inflicting increasing damage on Iran's oil-based economy he had not seen any sign that Tehran was ready to give up its nuclear ambitions.
Several rounds of increasingly punitive United Nations and Western sanctions against Iran have failed to persuade it to halt its uranium enrichment program.
Iran Wednesday proclaimed advances in its nuclear know-how, including new centrifuges able to faster enrich uranium and loaded its first domestically produced batch of fuel into a research reactor.