Israel seriously considered bombing Iran's nuclear sites earlier this year but U.S. President George W. Bush refused to support such a strike, a British newspaper reported on Friday.
The Guardian said Israeli prime minister Ehud Olmert raised the issue with Bush in a private one-on-one meeting on May 14 in Jerusalem.
According to "European diplomatic sources," Bush said he would not support such a strike because of fears of retaliation, possibly on American targets in Iraq and Afghanistan, and concern that the Israelis would fail to fully disable Iran's nuclear facilities, the newspaper said.
Olmert "took it (the refusal of a U.S. green light) as where they were at the moment, and that the U.S. position was unlikely to change as long as Bush was in office," said one source.
The newspaper said that even if Israel had wanted to go ahead without Washington's agreement, its planes would be unable to reach Iran without passing through U.S.-controlled airspace above Iraq.
Iran would assume that Washington had approved the strike, raising the prospect of an attack against the United States, it said.
Israel considers Iran, the world's fourth-largest oil exporter, its greatest threat because of Tehran's nuclear program and repeated statements by its leaders predicting the demise of Israel.
The West accuses Iran of trying to develop nuclear weapons, while Tehran has insisted its program is for peaceful purposes.
"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," The Guardian quoted Olmert spokesman Mark Regev as saying.
U.S. National Security Council spokesman Gordon Johndroe said he would not comment on any private conversations the president had.
Washington says it wants a diplomatic solution to the standoff but has not ruled out military action as a last resort.
The Associated Press and Reuters contributed to this report.