Iran's nuclear agreement with world powers has drawn strong criticism from Israel and silence from its main Gulf rival, Saudi Arabia.
Under the deal reached in Geneva early Sunday, Iran must limit its enrichment of uranium and freeze reactor construction.
Israel and Saudi Arabia have long feared Iran will divert those activities to make atomic weapons that could threaten their interests. Iran says its nuclear program is peaceful.
In return for Iran's concessions, the United States and five other world powers agreed to ease some international sanctions on Iran's economy.
Israeli Prime Minister Benjamin Netanyahu told the Israeli Cabinet the Geneva agreement is a "historic mistake" that makes the world "a much more dangerous place." Israel wants more sanctions on Iran and a complete dismantling of its nuclear facilities.
The rulers of Saudi Arabia, Qatar and Kuwait met Saturday as Iran and the world powers finalized the nuclear deal.
None of the three Gulf states had commented on the agreement by late Sunday. But Sunni Arab Gulf leaders have expressed concerns in the past about what they see a campaign by Shi'ite Iran to boost its regional influence.
Israeli leaders see a nuclear-armed Iran as a threat to their nation's existence due to Iran's frequent calls for Israel's demise. Netanyahu said Israel will "not allow Iran to have a nuclear weapons capability."
President Barack Obama offered reassurance late Saturday, saying Washington's commitment to Israel and to its Gulf partners will "remain firm." He also said those nations have "good reason to be skeptical about Iran's intentions."
In an interview with CNN, Secretary of State John Kerry said the deal with Iran will make Israel "safer" because it is designed to expand the amount of time Iran would need to make a nuclear weapon.
Two Gulf states gave a cautious welcome to the Geneva agreement. The United Arab Emirates expressed hope that it will lead to a permanent deal that preserves stability in the region and protects it from nuclear proliferation. Bahrain said it hopes there will be an end to "fear" in the region.
The deal also won praise from Iran's neighbor, Iraq, and main regional ally, Syria, two Arab nations not led by Sunnis.
Iraq's Shi'ite-led government called the agreement a step forward for solving regional problems. The government of Syrian President Bashar al-Assad said the deal is proof that negotiations are the best way to resolve a conflict.
Assad is a member of the Alawite sect of Shia Islam. Iran has been supporting him as he fights off a two-year long rebellion against his autocratic rule.
The government of Palestinian President Mahmoud Abbas hailed the Iran nuclear deal as an "important message for Israel to realize that peace is the only option in the Middle East." Israel is believed to be the only nuclear-armed nation in the region. It neither confirms nor denies that status.
U.N. Secretary-General Ban Ki-moon welcomed the Geneva pact and urged the governments involved to "do everything possible to build on this encouraging start."