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.

For the full text of the speech click here.

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. 

He further noted that it is "important that the world is with us if we have to act."

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. 

Following Biden's speech, AIPAC spokesperson Marshall Wittmann issued a statement saying: “We are very pleased by the vice president’s strong statement that the president is not bluffing in his commitment to prevent Iran from obtaining a nuclear weapon. It was a strong and eloquent speech.” 

Prime Minister Benjamin Netanyahu did not attend the conference, instead opting to deliver a video message shortly after Biden's speech.

Ehud Barak, the outgoing defense minister, addressed the conference in person on Sunday. Barak called on the U.S. to set up a “regional security framework” that would unite Middle East countries around the “joint challenges of radical Islamist terror, border security, missile defense and Iran.”