Russian President Vladimir Putin spoke by phone to leaders of three Arab Gulf states on Monday, offering to use Moscow's ties to Iran to try to help restore calm to the Middle East following U.S. and Israeli strikes, which he condemned.

In a series of calls with the leaders of the UAE, Bahrain and Qatar, Putin criticised the U.S.-Israeli strikes on Iran, which the Kremlin described as "unprovoked aggression".

Earlier, the Kremlin said that Moscow remained in constant contact with the Iranian leadership.

Moscow sees its strategic partnership with Iran as central to maintaining its remaining clout in the Middle East, where its influence took a hit when their mutual ally Syrian President Bashar al-Assad was toppled 15 months ago.

Although Russia stands to benefit from higher oil prices and may welcome Washington's focus shifting away from Ukraine, the U.S.-Israeli air war also runs counter to Moscow's desire for a multilateral world order in which the U.S. is not dominant.

Arab states in the Gulf, all close U.S. allies, have come under Iranian drone and missile attack since the United States and Israel launched their air strikes on Saturday.

According to the Kremlin readout of Putin's call with UAE President Mohammed bin Zayed Al Nahyan, the Russian leader offered to act as a conduit by conveying the UAE's complaints about being attacked to Tehran.

During the call, "both sides emphasised the need for an immediate ceasefire and a return to the political and diplomatic process," the Kremlin added.

In Putin's call with Qatar's Emir Sheikh Tamim bin Hamad al-Thani, the Kremlin said both leaders had spoken of their concern about the conflict widening and the risk of third countries becoming involved. And Putin told Bahrain's King Hamad bin Isa Al Khalifa that Russia was ready to do all it could to stabilise the situation in the region.

Putin on Sunday condemned the killing of Iranian Supreme Leader Ayatollah Ali Khamenei as a "cynical" murder. The Russian Foreign Ministry has accused the U.S. and Israel of plunging the Middle East "into an abyss of uncontrolled escalation".

But Moscow is also keen not to alienate the administration of President Donald Trump as Washington brokers peace talks on Ukraine. Kremlin spokesman Dmitry Peskov said Moscow wanted those talks to continue.

"We have our own interests that we must protect, and it is in our interests to continue these negotiations (on Ukraine)," said Kremlin spokesman Dmitry Peskov.