Israeli PM Benjamin Netanyahu has said time is running out to put a stop to Iran's nuclear programme.
Speaking to a pro-Israel conference in the US, Mr Netanyahu said he could not allow his people to "live in the shadow of annihilation".
Israel fears Iran is seeking to develop nuclear weapons, and speculation of a pre-emptive strike has recently grown.
US President Barack Obama has said there is still time for diplomacy, but that all options remain open.
Tehran insists its nuclear plans are peaceful.
Speaking to some 13,000 delegates at the American-Israel Public Affairs Committee (Aipac) on Monday night, Mr Netanyahu reiterated that Israel was "determined to prevent Iran having nuclear weapons".
"Unfortunately, Iran's nuclear programme has continued to march forward," he said.
"Israel has waited for diplomacy to work, we've waited for sanctions to work. None of us can afford to wait much longer.
"As prime minister of Israel I will never let my people live in the shadow of annihilation."
He stressed that all options were on the table, but that containment - leaving Iran to develop its programme under monitoring - was "not an option".
"The Jewish state will not allow those who seek our destruction the means to achieve that goal. A nuclear armed Iran must be stopped," Mr Netanyahu told Aipac.
In a meeting with Mr Netanyahu at the White House on Monday, Mr Obama said the bond between their countries was "unbreakable".
He said the US believed there was "still a window that allows for a diplomatic resolution", on Iran, but added that the US would consider "all options".
"I know that both the prime minister and I prefer to resolve this diplomatically," Mr Obama said. "We understand the costs of any military action."
For his part, Mr Netanyahu said: "I believe that's why you appreciate, Mr President, that Israel must reserve the right to defend itself." He went on to add that Israel must remain "the master of its fate".
The two leaders are said to have a cool relationship. In May 2011, during a visit to Washington, correspondents noted the frosty body language between the two leaders.
In his own address to Aipac on Sunday, Mr Obama said there had been too much "loose talk" of war with Iran, which was benefiting Tehran as it was driving up the price of oil, which funds the nuclear programme.
He said Iran was isolated and there was an opportunity "for diplomacy - backed by pressure - to succeed".
"Iran's leaders should know that I do not have a policy of containment - I have a policy to prevent Iran from obtaining a nuclear weapon," he said.
"And as I've made clear time and again during the course of my presidency, I will not hesitate to use force when it is necessary to defend the United States and its interests."
After years of international pressure and the repeated failure of negotiations and offers of talks with Tehran, talk has grown in recent months of a pre-emptive strike against Iranian nuclear facilities.
The US has pushed for the imposition of ever-stricter sanctions against Iran, including recent curbs on its central bank and its ability to export oil to the West.
Yet despite the ratcheting up of sanctions, speculation has been mounting that Israel might choose to attack Iran sometime during 2012.
Hours before the US-Israeli meetings the head of the UN nuclear agency, Yukiya Amano, reiterated that his organisation had "serious concerns" that Iran could be hiding secret work on developing atomic weapons.
Citing a recent agency report, he said the organisation was unable "to conclude that all nuclear material in Iran is in peaceful activities".