China is concerned about a row between Iran and Saudi Arabia, calling on countries involved to exercise restraint in handling differences.

"At present, the situation in the Middle East is complex and uncertain," Chinese Foreign Ministry spokeswoman Hua Chunying said at a regular press briefing on Tuesday.

On Sunday, Saudi Arabia cut off diplomatic relations with Iran after protesters stormed its embassy in Tehran to protest against the execution of prominent Shiite cleric Sheikh Nimr Baqir al-Nimr.

On Monday, three Sunni-led countries -- Bahrain, Sudan and the United Arab Emirates -- joined Saudi Arabia in severing or downgrading diplomatic ties with Iran, adding to the fraught atmosphere in the region.

Hua expressed the hope that relevant countries can keep calm, show restraint, properly resolve differences and promote regional stability through dialogue and consultation, which are in line with the common interests of countries in the region.

"We have noticed that many countries of the international community have expressed similar concerns and positions," Hua said.