Israeli Prime Minister Benjamin Netanyahu blasted details of an expected deal between the U.S. and Iran that would freeze elements of Tehran's nuclear program along with limited sanctions relief just as Secretary of State John Kerry was arriving in Geneva to finalize the agreement.

Netanyahu called it “the deal of the century for Iran” but a “very, very, bad” deal for the international community. The Israeli leader said he learned about the parameters of the agreement when he met with Kerry on Thursday at Ben Gurion Airport in Tel Aviv before he left for Geneva.

“I reminded him that he said that no deal is better than a bad deal,” Netanyahu said in a statement. “That the deal that is being discussed in Geneva right now is a bad deal. It's a very bad deal.”

Iran, Netanyahu said, is not required to dismantle even one centrifuge yet the U.S. and the international community is providing sanctions relief for the first time in years.

“Iran gets everything that it wanted at this stage and it pays nothing,” Netanyahu said. He said the sanctions regime in place now is “why Iran is under severe pressure.”

Netanyahu urged Kerry not to “rush to sign” but “to wait, to reconsider, to get a good deal.”

Kerry is scheduled to meet with Iran's foreign minister, Mohammad Javad Zarif, and the European Union's foreign policy chief, Catherine Ashton, who is overseeing the negotiations over Iran's nuclear program.

A State Department spokesman said Thursday that Kerry was heading to Geneva “in an effort to help narrow the differences in the negotiations.”

U.S. officials Thursday said the P5+1 group, which is conducting talks with Iran on its nuclear program, was weighing the possibility of easing some sanctions on Tehran to help further advance negotiations. But American officials say any agreement reached Thursday would only be the first phase, in which Iran would agree to stop progress on its nuclear program for six months to allow negotiators to hash out a more comprehensive agreement. In exchange, the U.S. and the international community would agree to provide some sanctions relief.

The Obama administration has launched a new round of talks with Iran after the election earlier this year of President Hassan Rouhani, who campaigned on a promise of getting the sanctions lifted and has reached out to the U.S. and toned down some of Tehran’s anti-Western rhetoric.

Iran insists that its nuclear program is for peaceful energy purposes, but the U.S. and key allies, including the European Union and Israel, fear Iran is building nuclear weapons.

White House spokesman Jay Carney Thursday said that the P5+1 group, which consists of the U.S., United Kingdom, France, Germany, Russia and China, is engaged in “serious and substantial” negotiations.

He cautioned though that any relief from the sanctions regime would be part of a “phased approach” and linked to steps preventing Iran’s “nuclear program from moving forward and potentially rolling back parts of it.”

He added that sanctions would be “maintained until there is a final, verifiable agreement” and that any relief could be “terminated” if Iran fails to cooperate, or uphold its commitment to treaties and international bodies.

But the White House effort faces opposition on Capitol Hill, where lawmakers may consider legislation to block the administration from easing any sanctions on Iran.

Meghashyam Mali contributed to this report.