US President Barack Obama said a framework agreement reached at talks in Switzerland on Iran's nuclear program is "a good deal" that would, if fully implemented, prevent Tehran from obtaining a nuclear weapon and help make the world safer.

Speaking at the White House Rose Garden, Obama said he would talk with Israeli Prime Minister Benjamin Netanyahu - a fierce critic of an Iran deal - as well as US congressional leaders later on Thursday, and had already spoken with Saudi Arabia's King Salman.

"A diplomatic solution is the best way to get this done," he added, especially when compared to military action.

Obama, who delayed a scheduled trip to Kentucky and Utah to make the statement after negotiators announced the agreement, addressed critics of the talks with Iran and acknowledged that the framework deal alone would not erase distrust between the Washington and Tehran.

"Of course, this deal alone, even if fully implemented, will not end the deep divisions and mistrust between our two countries. We have a difficult history between us," Obama said.

The framework agreement would cut off every pathway that Iran could take to develop a nuclear weapon, Obama said as he sought to sell the deal to the American public and US lawmakers.

"In the coming days and weeks, my administration will engage Congress once again about how we can play - how it can play a constructive oversight role. I'll begin that effort by speaking to the leaders of the House and Senate today," he said.

Israel dismissed celebration of a nuclear framework deal between major powers and Iran on Thursday, calling it detached from reality, and vowed to continue lobbying to prevent a "bad" final agreement.

Obama has said he would speak to Netanyahu later on Thursday. Netanyahu was expected to postpone any comment until after that conversation takes place.

"I will be speaking with the Prime Minister today to make clear that there will be no daylight, there is no daylight, when it comes to our support for Israel's security and our concerns about Iran's destabilizing policies and threats toward Israel," Obama said.

Iran and world powers reached a framework agreement on Thursday on curbing Iran's nuclear program for at least a decade after eight days of marathon talks in Switzerland.

The tentative agreement clears the way for talks on a future comprehensive settlement that should allay Western fears that Iran was seeking to build an atomic bomb and in return lift economic sanctions on the Islamic Republic.