President Barack Obama warned that he is not bluffing about attacking Iran if it builds a nuclear weapon, but in an interview published Friday, Obama also cautioned U.S. ally Israel that a premature attack on Iran would do more harm than good.

In his most expansive remarks on the issue thus far, Obama told The Atlantic magazine that Iran and Israel both understand that "a military component" is among a mix of many options for dealing with Iran, along with sanctions and diplomacy.

That is the most direct threat he has issued during months of escalating tension with Iran over its disputed nuclear development program.

'I don't bluff... when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say.'—U.S. President Barack Obama

His comments appeared aimed more at Israel and its supporters in the United States than at Iran. Obama addresses the influential American Israel Public Affairs Committee on Sunday and meets with Israeli Prime Minister Benjamin Netanyahu Monday at the White House. Netanyahu will also address AIPAC.

"I think that the Israeli government recognizes that, as president of the United States, I don't bluff," he said in the interview. "I also don't, as a matter of sound policy, go around advertising exactly what our intentions are. But (both) governments recognize that when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say."

Israeli PM calls Iran a 'grave threat'

Netanyahu, speaking Friday ahead of a meeting in Canada with Prime Minister Stephen Harper, called Iran's nuclear ambitions a "grave threat to the peace and security of the world, and I think it's important that the international community not allow this threat to materialize."

"As for Israel, like any sovereign country, we reserve the right to defend ourselves against a country, against a country that calls and works for our destruction," Netanyahu said.

Obama will try to convince Netanyahu to postpone any plans his government may have to unilaterally attack Iran's nuclear facilities in coming months. An attack that soon would not carry U.S. backing, and the U.S. would probably not be involved in planning or executing it.

Nonetheless, it could force the United States into a new conflict and an arms race in the Middle East, as Obama made clear in the lengthy interview. It also could allow Iran to paint itself as the victim and draw new support that would undermine rather than enhance Israel's security, Obama warned.

"At a time when there is not a lot of sympathy for Iran and its only real ally (Syria) is on the ropes, do we want a distraction in which suddenly Iran can portray itself as a victim?" Obama said.

At the same time, Obama has consistently refused to renounce a military option for the United States down the road. The dispute with Israel is over the timing and efficiency of such a strike, not whether one is ever appropriate. The difference of opinion has quickly come to dominate the U.S.-Israeli relationship and the U.S. strategy for dealing with a nuclear Iran is a major issue for American Jewish voters in this election year.

Israeli leaders have strongly hinted that they want to hear clearer terms from Obama for what the United States would do if Iran crosses the threshold from nuclear energy to nuclear weapons. Until now, Obama has said a nuclear Iran is unacceptable but has not spelled out just what the U.S. would do or when.

'Nobody has announced a war'

In the interview, Obama did go further than he has before. He explicitly referred to the possible use of military force, and he firmly rejected the notion that the United States might settle for a strategy of deterring Iran from using a nuclear weapon.

"You're talking about the most volatile region in the world," he said. "It will not be tolerable to a number of states in that region for Iran to have a nuclear weapon and them not to have a nuclear weapon. Iran is known to sponsor terrorist organizations, so the threat of proliferation becomes that much more severe. "

He also pointed to economic turmoil in Iran and reiterated that sanctions against the Iranian regime are starting to bite.

In a series of recent meetings with Israeli leaders, administration officials are believed to have sought to persuade the Jewish state to give sanctions more time to work and to hold off on any military strike. Speaking Thursday to reporters, White House press secretary Jay Carney said Obama believes there is still "time and space" for those measure to persuade the Iranian regime to take a different course.

Israeli officials acknowledge the pain in Iran but have publicly expressed doubt those measures will ever cause Iran's clerical leaders to change course.

Obama wasn't so sure. "They're sensitive to the opinions of the people and they are troubled by the isolation that they're experiencing," he told the Atlantic. "They know, for example, that when these kinds of sanctions are applied, it puts a world of hurt on them."

Though Obama emphatically portrays himself as one of Israel's best friends, touting military and other ties, his relationship with Netanyahu has at times been frosty. The two have sparred publicly over Jewish settlements on the West Bank, with Netanyahu pushing back on Washington's efforts to move forward on peace talks with the Palestinians.

The Iran issue has risen to the forefront of his foreign policy. At a fundraiser in New York on Thursday night, an audience member shouted out, urging the president to avoid a war with Iran.

"Nobody has announced a war," Obama cautioned. "You're jumping the gun a little bit."