US President Barack Obama delivers remarks to AIPAC's annual policy conference in Washington, March 4, 2012. [Photo/Agencies]

WASHINGTON - 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 US 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 US fears that Israel might opt to strike Iran on its own if it is not convinced of US 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 US election looming in November and would be forced to give at least tacit support if Israel were to take military action against Iran.