Israeli Prime Minister Benjamin Netanyahu's public challenge to the White House to set "red lines" for Tehran could be an attempt to back off from plans for a unilateral strike on Iran's nuclear facilities, Israeli analysts said on Tuesday.

"Netanyahu has decided that he won't attack before the (US) elections because it's politically impossible because of American opposition, and it's impossible because of opposition within the Israeli establishment," said Shlomo Brom of Tel Aviv University's Institute for National Security Studies.

"He's looking for a way to preserve his prestige, and the way Israeli leaders often do that is by convincing the Israeli public that they're not suckers," Brom said.

Netanyahu's insistence on red lines was meant to convince Israelis he is driving a hard bargain and not caving in to western pressure, he said.

"I think this is all intended to give Netanyahu a ladder with which to climb down from the tree," he added.

Over the past week, the Israeli leader has repeatedly driven home the need to lay down a "clear red line" for Iran -- a boundary which, if crossed, could trigger immediate tough international action such as US-led air strikes.

"The world tells Israel: Wait, there's still time. And I say: wait for what? Wait until when?" Netanyahu said on Tuesday.

"Those in the international community who refuse to put red lines before Iran don't have a moral right to place a red light before Israel."

Eytan Gilboa of Bar Ilan University near Tel Aviv agrees Netanyahu and his Defence Minister Ehud Barak know they cannot make good on threats to bomb Iran without US compliance.

But rather than grandstanding for a domestic audience, Gilboa sees Netanyahu as genuinely pushing for reassurance from US President Barack Obama.

"I don't think that Israel has a military option without understandings with the United States," he told AFP.

"He is frustrated because he's not getting more explicit commitment from the United States.

"Perhaps one of the expected consequences of the verbal public exchanges is simply to get the United States to be more explicit, more precise and more committed to stopping Iran," he added.

The left-leaning Haaretz daily on Tuesday said that an unidentified senior British official recently brought "a stern message from British Prime Minister David Cameron against an uncoordinated Israeli strike on Iran at this time."

Neither the British embassy nor Netanyahu's office would comment on the report.

"The firm message of the UK envoy, together with a telephone conversation during the same period between Netanyahu and German Chancellor Angela Merkel and public remarks by high-ranking US officials in recent weeks have affected Netanyahu's and Barak's attitude to the Iran issue," the paper said.

"The combined weight of the messages coming from Western powers seems to have cooled the two men's enthusiasm for launching an uncoordinated attack on Iran."

Netanyahu believes a nuclear-armed Iran would pose an existential threat to Israel, but his repeated calls for the international community to establish a clear red line -- widely understood as a message to Washington -- on Monday appeared to fall on deaf ears.

"The president has said unequivocally he will not allow Iran to obtain a nuclear weapon," State Department spokeswoman Victoria Nuland told reporters.

"We are absolutely firm about the president's commitment here, but it is not useful to be parsing it, to be setting deadlines one way or the other, red lines," she said, promising "intensive consultations with Israel."

US Secretary of State Hillary Clinton also dismissed such a move.

"We're not setting deadlines. We're watching very carefully about what they do," she told Bloomberg radio on Sunday.

Nevertheless, says Tel Aviv University's Mark Heller, Netanyahu seems to believe that piling pressure on Obama could pay off, especially with presidential elections fast approaching.

"He wants to try his hand at pushing him in that direction and probably thinks the campaign season is as good an opportunity as any to do that," Heller told AFP.

"I think he would much prefer that the Americans got Iran to back off rather than leaving it to Israel."