Cheering crowds have welcomed home the Iranian negotiators who secured a nuclear deal with world powers, while Israel called it a "historic mistake," BBC News reported.

U.S. President Barack Obama telephoned Israeli Prime Minister Benjamin Netanyahu, seeking to reassure him of Washington's commitment to Israel.

Sunday's deal in Geneva prompted a fall in oil prices on markets on Monday, November 25.

Iran has agreed to curb some of its nuclear activities in return for about $7bn in sanctions relief.

Hundreds of cheering supporters greeted Iran's negotiators as they arrived back in Tehran on Sunday, after reaching an interim nuclear agreement with the U.S., Russia, China, France, the UK, and Germany.

Carrying flowers and Iranian flags at Tehran's Mehrabad airport, they hailed Iran's foreign minister, Mohammed Javad Zarif, as an "ambassador of peace" and chanted, "No to war, sanctions, surrender and insult".

Speaking to Iranian state television at the airport, Zarif said Iran was prepared to take the necessary steps to keep the deal on track. But he said the interim, six-month deal agreed in Geneva could be halted by Tehran at any stage.

Earlier, the U.S. President Barack Obama welcomed the deal, saying it would "help prevent Iran from building a nuclear weapon".

But Netanyahu said Israel would not be bound by the agreement, saying he had a "duty to speak out". "We cannot and will not allow a regime that calls for the destruction of Israel to obtain the means to achieve this goal."

His comments came as it was revealed that the U.S. and Iran had held a series of face-to-face talks in recent months that paved the way for the agreement but were kept secret even from their allies.

World powers suspect Iran's nuclear programme is secretly aiming at developing a nuclear bomb - a charge Iran has consistently denied.

The deal reached early on Sunday in Geneva will last for six months, while a permanent agreement is sought.