Israeli Prime Minister Benjamin Netanyahu urged world powers on Sunday to set a "clear red line" for Tehran's atomic program that would convince Iran they were determined to prevent it from obtaining nuclear arms.
Netanyahu's remarks suggested a growing impatience with Israel's main ally, the United States, and other countries that have been pressing him to give diplomacy and sanctions more time to work and hold off on any go-it-alone strike on Iran.
Recent heightened Israeli rhetoric has stoked speculation that Israel might attack Iran before the US elections in November, believing that President Barack Obama would give it military help and not risk alienating pro-Israeli voters.
"I believe the truth must be stated: The international community is not placing a clear red line for Iran and Iran does not see international resolve to stop its nuclear programme," Netanyahu told his cabinet.
"Unless Iran sees this clear red line and this clear resolve it will not stop moving forward with its nuclear programme, and Iran must not have nuclear weapons," he said, repeating his view that sanctions so far have not curbed Tehran's atomic ambitions.
Although Netanyahu did not single out Obama in his criticism, Israeli officials have said they hope for stronger language from the president about possible US military action.
Obama, who has had a frosty relationship with Netanyahu, has insisted he will not allow Iran to build atomic weapons and that all options are on the table.
Israel's popular YNet news website described the prime minister's latest comments as a stinging rebuke of Obama. In a US election year, Republican candidate Mitt Romney has also sharply criticised Obama's handling of Iran as not being tough enough.
And in another sign of a rift with Washington, Israeli officials voiced disappointment over recent remarks by the United States' top general signalling reluctance to intervene on Israel's behalf if it attacked Iran.
Tehran says it is refining uranium to fuel a planned network of nuclear power plants so that it can export more of its oil and gas. The United States and its allies accuse Iran of a covert bid to develop the capability to make nuclear bombs.
Israel, believed to have the only atomic arsenal in the Middle East, views a nuclear-armed Iran as a threat to its existence.
General Martin Dempsey, chairman of the US joint chiefs of staff, has suggested Washington would not be drawn into conflict with Iran should Israel attack.
"I don't want to be complicit if they choose to do it," Britain's Guardian newspaper quoted him on Friday as saying.
Gilad Erdan, Israel's environment minister, said on Israel Radio that Dempsey's remarks "were definitely not to our liking". Finance Minister Yuval Steinitz said the general's choice of words "was not the best".
Israeli officials have said Israel has yet to decide on whether to attack Iran, amid divisions within its security cabinet and warnings by military and security chiefs that a strike would have only a limited effect.
Netanyahu has said he will speak out about what he termed the dangers Iran poses to the world in an address this month to the UN General Assembly in New York. He is also expected to meet Obama during his visit, but no announcement has been made.
A senior Israeli official told Reuters last week Netanyahu would seek a firm pledge of US military action if Iran did not back down on uranium enrichment. Such a promise could dissuade Israel from attacking Iran alone, Israeli officials have said.
A United Nations report said on Thursday that Iran had more than doubled the number of centrifuges in its fortified bunker at Fordow since May, despite Western pressure and threat of Israeli attack. The new machines are not yet operating, the report said.
"The report confirms what I have been saying for a long time, international sanctions are a burden on Iran's economy but they are not in any way delaying the advancement of Iran's nuclear programme," Netanyahu told his cabinet.
"The Iranians are using the talks with the world powers to win time and to advance their nuclear programme," he said.
An Iranian general said that if Israel were to strike Iran, Israeli officials would be the target of retaliation, Iranian media reported on Sunday.
"In case of Israel's military attack against Iran, the officials of (Israel) will be among the first victims of such an attack," Mohammad Ali Assoudi, a brigadier general in the Islamic Revolutionary Guard Corps, told Iran's English-language Press TV.
His broadcast remarks gave no details, but Press TV paraphrased him as saying Israel's policies had induced hatred of its officials among residents of the occupied territories.
Iran has undertaken large-scale military manoeuvres this summer and unveiled upgrades to weapons it says are defensive, including what it said was a more accurate short-range missile.