The war, triggered by US and Israeli strikes on Iran, has threatened global energy security and trade, as well as China's oil supplies.

Beijing is a close partner of Tehran and condemned the killing of Ayatollah Ali Khamenei, but it has also criticised Iranian strikes against several Gulf states, including Saudi Arabia, since the outbreak of the conflict.

Beijing was "deeply concerned" by the current situation in the region, special envoy Zhai Jun told Foreign Minister Faisal bin Farhan during talks on Sunday, according to a Chinese foreign ministry readout.

"China urges all parties to immediately cease military operations, prevent further escalation of tensions, and avoid causing greater harm to the people of regional countries," he said.

"The sovereignty, security, and territorial integrity of the Gulf countries are inviolable, and any attacks on innocent civilians and non-military targets should be condemned."

In a separate meeting with Jasem Mohamed Al-Budaiwi, head of the Gulf Cooperation Council, Zhai called for a "return to the negotiating track as soon as possible".

China would "play a constructive role... to actively promote peace and stop the fighting", he said.

China's Foreign Minister Wang Yi said on Sunday that the war "should never have happened" and called for an end to fighting.