Israeli officials say they won't warn the US if they decide to launch a pre-emptive strike against Iranian nuclear facilities, according to one US intelligence official familiar with the discussions.

The pronouncement, delivered in a series of private, top-level conversations, sets a tense tone ahead of meetings in the coming days at the White House and Capitol Hill.

Israeli officials said that if they eventually decide a strike is necessary, they would keep the Americans in the dark to decrease the likelihood that the US would be held responsible for failing to stop Israel's potential attack.

The US has been working with the Israelis for months to persuade them that an attack would be only a temporary setback to Iran's nuclear program.

Israeli Prime Minister Benjamin Netanyahu and Defence Minister Ehud Barak delivered the message to top-level US visitors to the country, including the chairman of the Joint Chiefs of Staff, the White House national security adviser and the director of national intelligence, and top US legislators, all trying to close the trust gap between Israel and the US over how to deal with Iran's nuclear ambitions.