Obama is "not bluffing" on stopping Iran's nuclear drive: Biden

U.S. Vice President Joe Biden makes remarks at the conclusion of a roundtable discussion on gun control at Girard College in Philadelphia, Pennsylvania, February 11, 2013.

WASHINGTON (Reuters) - Vice President Joe Biden told America's biggest pro-Israel lobbying organization on Monday that President Barack Obama is "not bluffing" about the United States' determination to stop Iran from getting a nuclear weapon.

"The president of the United States cannot and does not bluff. President Barack Obama is not bluffing," he told the American Israel Public Affairs Committee (AIPAC) in a speech to its annual policy conference.

"We're not looking for war. We're ready to negotiate peacefully . But all options including military force are on the table," said Biden.

"While that window is closing, we believe there is still time and space (for diplomacy)," he added.

The United States and many of its allies suspect Iran may be using its civil nuclear program as a cover to develop atomic weapons, a possibility that Israel, which is regarded as the Middle East's only nuclear power, sees as a mortal threat.

Biden said that a nuclear bomb in Iranian hands would be an "existential threat" to Israel, poses danger to other U.S. allies in the Middle East and would destabilize the world.

"We have a shared strategic commitment. Let me make clear what that commitment is: It is to prevent Iran from acquiring a nuclear weapon, period," he said to loud applause from AIPAC, which has gathered some 13,000 activists in Washington this week.

Talks involving Iran and world powers in Kazakhstan about its nuclear work ended last week with an agreement to meet again.

But Western officials said Iran had yet to do anything concrete to allay their concerns about its nuclear aspirations, and Israeli leaders have warned that Tehran is using the negotiations to buy time to advance their nuclear program.

The United States, China, France, Russia, Britain and Germany offered modest relief from economic sanctions in return for Iran reining in its most sensitive nuclear activity but made clear that no breakthrough was in the offing quickly.

Obama will visit Israel before the Jewish holiday of Passover, which begins the week of March 25, Biden said.

(Reporting by Matt Spetalnick and Paul Eckert; Editing by Vicki Allen and Philip Barbara)