WASHINGTON (Reuters) - President Barack Obama warned on Sunday against "loose talk" of a war with Iran ahead of a crucial meeting in which he will urge Israel's prime minister to avoid a premature strike on the Islamic Republic's nuclear facilities.
On the eve of his talks with Benjamin Netanyahu, Obama used a speech to the pro-Israel U.S. lobbying group AIPAC to pledge his staunch support for the Jewish state and to argue that international sanctions on Iran must be given more time to work.
But there was no sign he and Netanyahu were moving any closer to agreeing on their approach to Iran.
Obama said the "bluster" about a military strike was counterproductive because it has been driving up global oil prices, boosting demand for Iran's oil and helping to offset the impact of sanctions on its economy.
"I firmly believe that an opportunity remains for diplomacy - backed by pressure - to succeed," Obama told the crowd of 13,000 people in a cavernous ballroom.
"I would ask that we all remember the weightiness of these issues, the stakes involved for Israel, for America, and for the world. Already, there is too much loose talk of war," he added.
Obama's meeting with Netanyahu on Monday comes amid U.S. fears that Israel might opt to strike Iran on its own if it is not convinced of U.S. resolve to stop Tehran from acquiring a nuclear weapon.
Such speculation has gained traction as Obama has faced election-year criticism from Republicans who question the strength of his support for Israel and accuse him of not taking a tough enough approach toward Iran.
Analysts say such criticism could lead Israel to calculate that Obama could ill afford a rift with the Jewish state with a U.S. election looming in November and would be forced to give at least tacit support if Israel were to take military action against Iran.
Speaking to reporters in Ottawa after Obama spoke, Netanyahu welcomed Obama's speech but highlighted parts of it where the U.S. president said he would "take no options off the table" - a reference to the possibility of military action if necessary to stop Iran from acquiring a nuclear weapon.
Netanyahu said he appreciated that Obama "made clear that when it comes to a nuclear-armed Iran, containment is simply not an option."
"Perhaps most important of all, I appreciated the fact that he said that Israel must be able to defend itself, by itself, against any threat," Netanyahu added.
Israeli President Shimon Peres, addressing the AIPAC conference just before Obama took the podium, said the United States and Israel shared the goal of preventing Iran from developing a nuclear weapon.
"There is no space between us," said Peres, a former leader of the center-left Labor Party whose post is largely ceremonial. Peres has often taken a softer line on Middle East issues than Netanyahu, who heads the right-wing Likud party.
Obama last week issued his most direct threat yet of U.S. military action against Iran, saying in an interview with the Atlantic magazine, "I don't bluff.
However, as he did in the AIPAC speech, Obama argued in the interview for focusing on sanctions as the course of action with the most likely chance of success.
At the AIPAC conference, Obama received the strongest applause when he spoke of the bond between the United States and Israel and when he said the United States had a profound interest in preventing Iran from getting a nuclear bomb. The audience gave him a standing ovation at the conclusion of the speech.
In addition to framing his views on Iran ahead of the talks with Netanyahu, one of Obama's aims in his remarks was to push back at Republican critics who have seized on differences between Netanyahu and Obama over Iran to argue he has not been supportive enough of a key U.S. ally.
"There should not be a shred of doubt by now: when the chips are down, I have Israel's back," Obama said.
Speaking on NBC's Meet the Press, Republican presidential candidate Newt Gingrich said Obama's sanctions strategy "hasn't worked" and called on the president to do more to warn Iran of a potential military strike.
Mitt Romney, the Republican front-runner, told a campaign rally in Snellville, Georgia, that "if Barack Obama gets re-elected, Iran will have a nuclear weapon."
Romney, Gingrich and Republican candidate Rick Santorum are expected to address the AIPAC conference on Tuesday.
Obama signed a law in December threatening sanctions on financial institutions that deal with Iran's central bank, and the EU in January announced an embargo on Iranian oil imports from July 1.
A decline in Iranian oil sales in the past couple of months has been one of the leading factors in the rise in oil prices.
Additional reporting by Jeremy Pelofsky and Jim Wolf in Washington; Jeffrey Heller in Ottawa and Sam Youngman in Snellville, Georgia; Editing by Will Dunham and Stacey Joyce