JERUSALEM (AP) — President Barack Obama said Sunday that United States will not hesitate to attack Iran with military force to prevent it from acquiring a nuclear weapon, but he cautioned that “too much loose talk of war” recently has only helped Tehran and driven up the price of oil.

Speaking to a powerful pro-Israel lobby, Obama appealed to Israel for more time to let sanctions further isolate Iran. He sought to halt a drumbeat to war with Iran and hold off a unilateral Israeli strike against Iran’s nuclear facilities.

“For the sake of Israel’s security, America’s security and the peace and security of the world, now is not the time for bluster,” Obama told thousands at the annual American-Israel Public Affairs Committee’s policy conference. “Now is the time to let our increased pressure sink in, and to sustain the broad international coalition that we have built.”

Quoting Theodore Roosevelt, Obama said he would “speak softly, but carry a big stick” — and warned Iran not to test U.S. resolve.

Obama’s widely anticipated speech came one day before he meets at the White House with Israeli Prime Minister Benjamin Netanyahu, who planned to address AIPAC late Monday. Three GOP presidential candidates — Mitt Romney, Rick Santorum and Newt Gingrich — were scheduled to speak to the conference via satellite on Tuesday, a critical day in the campaign when 10 states vote.

To Israel and to Jewish voters in this country, Obama promoted his administration’s commitment to the Mideast ally.

“You don’t have to count on my words. You can look at my deeds,” Obama said. He defended his record of rallying to Israel’s security and political sovereignty, saying: “We have been there for Israel. Every single time.”

Obama’s comments were heavily laced with the politics of the campaign. He blamed distortions of his record on partisan politics.

The Israeli president, Shimon Peres, spoke before Obama and said that a nuclear Iran would be a menace to the world, not just to Israel’s security.

Peres, whose country sees its existence threatened by the potential development of nuclear arms, said: “Iran is an evil, cruel, morally corrupt regime. It is based on destruction and is an affront to human dignity.” He said Israel knows the horrors of war and does not seek one with Iran, “but if we are forced to fight, trust me. We shall prevail.”

Iran insists its nuclear program is for peaceful purposes. U.S, Israel and many allies see no sign of that, and Israeli leaders openly have discussed the possibility of a military strike.

“Let’s begin with the truth that you all understand: No Israeli government can tolerate a nuclear weapon in the hands of a regime that denies that Holocaust, threatens to wipe Israel off the map and sponsors terrorist groups committed to Israel’s destruction,” Obama said.

Obama said he would use all sources of American power, but that only true resolution would come from diplomacy.

U.S. officials worry that an Israeli attack on oil-power Iran could drive up pump prices and entangle the U.S. in a new Mideast confrontation during this year’s presidential election season. They want to give diplomacy and economic penalties more time to work.

The United States and Europe have pursued more severe banking and other economic penalties separately. The toughest take effect this summer and target Iran’s oil business and powerful central bank.

“I firmly believe that an opportunity remains for diplomacy — backed by pressure — to succeed,” Obama insisted.

And in his greatest detail to date, Obama spelled out the consequences of a military campaign against Iran.

“I would ask that we all remember the weightiness of these issues,” Obama said. “Already, there is too much loose talk of war.”

The economic implications were on Obama’s mind, too, as gas prices soar to the forefront of American concern ahead of the election.

In Israel, Foreign Minister Avigdor Lieberman said American pressure would not affect Israeli thinking on how to cope with the threat.

“We are an independent sovereign state, and at the end of the day, the state of Israel will make the most correct decisions as we understand them.”

Copyright 2012 The Associated Press.