"We urge all parties to immediately take measures to cool down the tensions, prevent the region from falling into greater turmoil, and create conditions for returning to the right track of resolving issues through dialogue and negotiations," Chinese foreign ministry spokesman Guo Jiakun said.

Israel's surprise assault on Iran last week, launched after decades of enmity and a prolonged shadow war fought through proxies and covert operations, has touched off the most intense fighting yet and triggered fears of a lengthy conflict that could engulf the Middle East.

Israel says its attacks have hit military and nuclear facilities and killed many top Iranian commanders and atomic scientists, although a senior US official said on Sunday that US President Donald Trump told Israel to back down from a plan to kill supreme leader Ayatollah Ali Khamenei.

China's top diplomat Wang Yi held phone calls with his Israeli and Iranian counterparts on Saturday, the foreign ministry said, in which he made clear to both Beijing's support for Tehran.

China enjoys close ties with Iran, being its largest commercial partner and the main buyer of its oil with Tehran still under crushing US sanctions.

Guo said on Monday "all relevant parties should immediately take steps to put the brakes on the escalation and to cool down the tensions".

"Force cannot bring lasting peace," he said.

"China will continue to maintain communication with the relevant parties, and promote peace and encourage dialogue, to prevent further turbulence in the region," he said.