By Mark Felsenthal and Matt Spetalnick
NEW ORLEANS/WASHINGTON (Reuters) - U.S. President Barack Obama called Prime Minister Benjamin Netanyahu on Friday after the Israeli leader delivered a stinging rebuke to Washington over a deal taking shape in talks between Iran and world powers seeking to curb Tehran's nuclear program.
The telephone call marked an apparent bid by Obama to tamp down growing unease over the emerging Iran deal among the United States' Middle East allies, including Saudi Arabia, as well as mounting opposition to the plan on Capitol Hill.
U.S. Secretary of State John Kerry, who flew to Geneva to join the high-stakes talks after what was described as a tense meeting with Netanyahu in Jerusalem, was seeking to close what he called "important gaps" with Iran over the terms of an agreement.
"The president provided the prime minister with an update on negotiations in Geneva and underscored his strong commitment to preventing Iran from obtaining a nuclear weapon, which is the aim of the ongoing negotiations," the White House said, adding that they agreed to continue "to stay in touch on this issue."
An Obama administration official said the call between the two leaders - who have a history of strained relations over Iran policy - was "very long" but declined to characterize the tone or provide further details.
Netanyahu warned Kerry and his European counterparts that Iran would be getting "the deal of the century" if they carried out proposals to grant Tehran limited, temporary sanctions relief in exchange for a partial suspension of its nuclear program and a pledge not to expand it.
"Israel utterly rejects it and what I am saying is shared by many in the region, whether or not they express that publicly," Netanyahu told reporters in Jerusalem.
Israel, believed to be the Middle East's only nuclear-armed power, has left open the prospect of military strikes on Iran's nuclear sites if diplomacy fails to halt its atomic drive.
White House spokesman Josh Earnest responded earlier by saying it was premature for Israel and Saudi Arabia to criticize what was still being deliberated in Geneva.
But he said the United States and close ally Israel were "in complete agreement about the need to prevent Iran from obtaining a nuclear weapon."
Saudi Arabia also has complained bitterly about the U.S. thaw in relations with Shi'ite Muslim Iran, the main regional rival of the Sunni-ruled kingdom.
Tehran is seeking relief from financial sanctions imposed by the United States and the European Union that have slashed its oil sales, severely hurting its economy.
Obama said on Thursday that he was open to "modest relief" on sanctions if Iran halts advancements on its nuclear program as talks on a permanent deal continue.
Washington and its allies believe Tehran is using its civilian nuclear program as a cover for seeking the ability to make a weapon, a charge Iran denies.
PUSH FOR FURTHER SANCTIONS
U.S. lawmakers have threatened to slap new sanctions on Iran even as the talks in Geneva have appeared to progress, despite White House appeals to hold off while it tests the diplomatic waters.
Kerry made an unscheduled trip to Geneva on Friday and was due to attend further talks on Saturday.
The Senate banking committee may introduce a bill with new sanctions on Iran's oil sales after similar legislation was passed by the House of Representatives in July. And some Republicans are considering introducing a package of tighter Iran sanctions as an amendment to a defense authorization bill that is expected to be debated next month.
"We need to see the details, but if there really is a deal this bad, lawmakers are going to have to explore their options," a senior aide to a senator said on Friday. Pro-Israel sentiment runs high on both sides of the aisle on Capitol Hill.
Eric Cantor, majority leader in the Republican-controlled House, said the emerging deal in Geneva would fall short if it failed to completely halt Iran's nuclear program.
"We should not race to accept a bad deal, but should keep up the pressure until the Iranians are willing to make significant concessions," he said.
Criticism also has begun bubbling up from some leading pro-Israel groups in Washington. White House officials met some of the more hawkish American Jewish leaders last week but failed to win broad support for a pause in further sanctions against Iran.
"Any deal that breathes life back into Iran's economy in return for token and superficial moves that put Tehran no further from nuclear breakout ... appears to be a horrific strategic error," said Josh Block, chief executive officer of The Israel Project, a non-partisan, pro-Israel organization.
J Street, a more liberal lobbying group, took a different tack, urging supporters on its website to "tell your senators: don't undermine Iran negotiations with new sanctions."
There was no immediate comment on the Geneva talks from the largest and most influential pro-Israel lobby, the American Israel Public Affairs Committee, or AIPAC.
(Additional reporting by Tim Gardner, Roberta Rampton and Patricia Zengerle; Editing by Alistair Bell and Mohammad Zargham)