VIDEO: Obama: World Must Press Iran

We`ve got to do that before Israel feels like its back is to the wall.

U.S. Democratic presidential candidate Barack Obama said on Monday the world must increase pressure on Iran because of its nuclear program before Israel feels it has its "back to the wall."

"My job as president would be to try to make sure that we are tightening the screws diplomatically on Iran, that we've mobilized the world community to go after Iran's program in a serious way, to get sanctions in place so that Iran starts making a difficult calculation," Obama said in response to a voter question at a campaign event in Iowa.

"We've got to do that before Israel feels like its back is to the wall," he said.

Obama was asked whether Israel felt it had a "green light" to take military action against Iran if there was not enough progress made soon by the United States and its allies to contain Tehran's nuclear ambitions.

"I don't want to speculate on whether or not Israel feels like it has a green light or not because that would be speculation," he said.

"What is not speculation is that we have to act much more forcefully and effectively on the world stage to contain Iran's nuclear capabilities," he said.

Obama, who is vying against Republican John McCain, spent two nights in Israel in July as part of a weeklong tour abroad and met with several Israeli officials.