China's President Xi Jinping has urged Donald Trump and North Korea to avoid "words and actions" that worsen tensions, state media says.
Mr Trump and North Korea have been exchanging hostile rhetoric, with the US president threatening to rain "fire and fury" on the North.
But China, North Korea's only major ally, has been urging restraint.
A White House statement said the US and China agreed North Korea must stop "provocative and escalatory behaviour".
Long-standing tensions over North Korea's nuclear programme worsened when it tested two intercontinental ballistic missiles in July.
The regime was also angered by last week's UN decision to increase economic sanctions against it.
According to Chinese state media, Mr Xi told Mr Trump in a phone call that "all relevant parties" should stop "words and deeds" that would exacerbate the situation.
Mr Xi also stressed China and the US share "common interests" over denuclearisation and maintaining peace on the Korean peninsular.
A White House statement on the phone call did not mention the apparent plea to the US president.
It stressed the two men enjoyed a close relationship, which will "hopefully lead to a peaceful resolution of the North Korea problem".
President Trump has previously chided China for not reining in North Korea, saying it could do "a lot more".
From 'fire and fury' to 'locked and loaded'
Tuesday: "North Korea, best not make any more threats to the United States," Mr Trump tells reporters. "They will be met with fire and fury like the world has never seen"
Wednesday: Mr Trump boasts that the US nuclear arsenal is "more powerful than ever"
Thursday: He says that his "fire and fury" warning maybe "wasn't tough enough". Asked what would be tougher than fire and fury, he replies, "you'll see"
Friday: The US president warns that military solutions are "locked and loaded" should North Korea "act unwisely".
Military solutions are now fully in place,locked and loaded,should North Korea act unwisely. Hopefully Kim Jong Un will find another path!— Donald J. Trump (@realDonaldTrump) August 11, 2017
On Friday he issued a fresh threat against North Korea, saying it should expect "big, big trouble" if anything happens to the US territory of Guam.
But he added: "Hopefully, it will all work out. Nobody loves a peaceful solution better than President Trump, that I can tell you."
On Friday, US Defence Secretary James Mattis said America still hopes to solve the North Korea crisis using diplomacy.
He said war would be "catastrophic" and that diplomacy was gaining results.
North Korea has announced plans to fire missiles near the Pacific territory of Guam, but there is no indication an attack is imminent.
For its part Pyongyang has accused Mr Trump of "driving" the Korean peninsula to the "brink of a nuclear war".
Moscow said the exchange of threats between Washington and North Korea "worry us very much" and Germany has also expressed alarm.
Foreign Minister Sergei Lavrov rated the risk of military conflict as "very high" as he put forward a joint Russian-Chinese plan to defuse the crisis.
German Chancellor Angela Merkel said there was no military solution, and "an escalation of the rhetoric is the wrong answer."
White House conducting 'behind-the-scenes diplomacy' with North Korea - reports
Despite the rhetoric from both sides, the Trump administration has been conducting behind-the-scenes diplomacy with North Korea for several months, the Associated Press news agency reports.
Washington has been addressing the issue of Americans detained in the country and escalating tensions on the peninsula, according to AP.
Joseph Yun, the US envoy for North Korea, and Pak Song-Il, a senior North Korean diplomat at the UN, are said to be leading the talks.
Tensions have risen since North Korea tested two intercontinental ballistic missiles in July.
The regime was further angered by last week's UN decision to increase economic sanctions against it.
North Korea said it was finalising a plan to fire medium-to-long-range
rockets towards Guam, where US strategic bombers are based, along with more than 160,000 US citizens.
There has been no indication that any actual attack on the Pacific island is imminent.
China's state-run Global Times newspaper wrote that Beijing should stay neutral if North Korea launches an attack that threatens the US.
But it also said that if the US and South Korea attacked North Korea to force regime change, then China must intervene to prevent it.
Meanwhile, Australian Prime Minister Malcolm Turnbull said his nation would be prepared to join a conflict against North Korea if the US came under attack.
Australia would honour its commitment under a 1951 treaty, he said, "as America would come to our aid if we were attacked".