U.S. Secretary of State John Kerry told the Council on Foreign Relations think tank on Friday that should Congress rejects the nuclear deal with Iran, Israel might find itself more isolated and "more blamed by the international community."

Also on Friday, Kerry said in an interview with NBC that it would be a "huge mistake" for Israel to take unilateral military action against Iran.

Kerry was asked in the "Today" show interview if the nuclear deal would make an Israeli military or cyberattack on Tehran more likely.

"That'd be an enormous mistake, a huge mistake with grave consequences for Israel and for the region, and I don't think it's necessary," Kerry said.

Kerry defended the deal Thursday during his first hearing with the Senate Foreign Relations Committee, and stressed that at no stage in the nuclear deal has the U.S. promised to help Iran defend itself from any Israeli attack.

"We plan to be fully coordinated with Israel" along every step of the way, Kerry said, adding that he does not foresee any scenario in which the U.S. will be at odds with Israel over the issue.

Kerry's appearance before the committee marked the beginning of the legislative oversight process that lawmakers will lead in the coming two months. Congress has until September 17 to approve the accord which will see Iran scale back its contested nuclear program and agree to international inspections of its alleged nuclear sites in return for an end to a crippling sanction regime.