Israel seriously considered bombing Iran's nuclear sites earlier this year but US President George W Bush refused to support such a strike, a British newspaper reported on Friday.
Quoting senior European diplomatic sources, The Guardian said Israeli prime minister Ehud Olmert raised the issue with Bush in a one-to-one meeting May 14.
Bush said he would not support such a strike because of fears of retaliation, possibly on US targets in Iraq and Afghanistan, and concerns that the Israelis would fail to disable Iran's nuclear facilities anyway, it said.
The newspaper noted that even if Israel had wanted to go ahead without Washington's agreement, its planes would be unable to reach Iran without passing through US-controlled airspace above Iraq.
Iran would be bound to assume that Washington approved the strike, raising the prospect of an attack against the United States, it said.
Israel considers Iran its greatest threat, because of Tehran's accelerating nuclear programme and repeated statements by its leaders predicting the Jewish state's demise.
Israel and the United States accuse Iran of trying to develop nuclear weapons, while Tehran has insisted its programme is entirely peaceful.
Neither the United States nor Israel the Middle East's sole, if undeclared, nuclear armed state has ruled out a military response to the nuclear standoff.
Olmert's spokesman, Mark Regev, told The Guardian: "The need to prevent Iran from obtaining nuclear weapons is raised at every meeting between the prime minister and foreign leaders. Israel prefers a diplomatic solution to this issue but all options must remain on the table."