The Asian neighbours have both sought to mediate in the Middle East to prevent the conflict from escalating, with Islamabad saying it was ready to host "meaningful talks" between the United States and Iran.

Pakistani Foreign Minister Ishaq Dar, who is also deputy prime minister, is visiting Beijing where he will meet with top Chinese diplomat Wang Yi for talks on international and bilateral issues.

"The two foreign ministers will strengthen strategic communication and coordination on the Iran situation and... make new efforts toward advocating for peace," Beijing's foreign ministry spokeswoman Mao Ning told a press conference, calling China and Pakistan "all-weather" strategic partners.

Dar's visit comes after he hosted his counterparts from Saudi Arabia, Egypt and Turkey on Sunday for talks about trying to end the war in the Middle East, which was triggered by US-Israeli strikes on Iran on February 28.

Concerns are running high about the impact of the fighting, including the choking of maritime traffic through the strategic Strait of Hormuz.

China is a key partner of Iran but has not announced military assistance to Tehran, instead repeatedly calling for a ceasefire.

Tehran has refused to admit to holding official talks with Washington but has passed a response to Trump's 15-point plan to end the war via Islamabad, according to an anonymous source cited by the Iranian Tasnim news agency.

Pakistan is one of China's closest partners in the region, but Beijing has called for "calm and restraint" in Islamabad's own conflict with Afghanistan.

A Chinese special envoy spent a week mediating between the two countries, Beijing's foreign ministry said this month.