0821 GMT March 21, 2018
Xi made the plea in a phone call hours after Trump ramped up his warnings, saying Pyongyang would "truly regret" taking hostile action against Washington, AFP reported.
The White House said in a statement that the two leaders "agreed North Korea must stop provocative and escalatory behavior" and that they are both committed to the denuclearization of the peninsula.
But the Chinese Foreign Ministry said Xi urged Trump to avoid "words and deeds" that would "exacerbate" the already-tense situation, exercise restraint and seek a political settlement.
Trump has been engaged all week in verbal sparring with the North over its weapons and missile programs, as US media reported Pyongyang has successfully miniaturized a nuclear warhead.
In a call with Guam Governor Eddie Calvo on Friday, Trump said the US military is prepared to "ensure the safety and security of the people of Guam" in response to Pyongyang's plans to launch missiles toward the Pacific territory.
Japanese media said Tokyo was deploying its Patriot missile defense system following Pyongyang's threat to fire ballistic missiles over the country toward Guam.
Trump had earlier brandished a threat of unleashing "fire and fury" on Pyongyang, then noted Thursday maybe that statement "wasn't tough enough". On Friday, the US president said the military was "locked and loaded, should North Korea act unwisely".
China, North Korea's biggest ally and trade partner, has been voicing concern at the mounting exchanges and a state-run newspaper suggested that Beijing should stay neutral if Pyongyang struck the US first.
Previously accused by Trump of not doing enough to rein in Pyongyang, China voted in favor of a series of wide-sweeping UN Security Council sanctions against North Korea last weekend.
According to the Chinese Foreign Ministry, Trump told Xi over the phone that he "fully understands China's role in the nuclear issue in the Korean Peninsula". Trump is expected to visit China later this year.
A commentary published in the North Korean state-run newspaper Minju Joson called the warnings from Trump and "other riffraff of the US...the last-ditch efforts and hysteric fit of those who are in the grip of despair" over the possible "tragic doom" of the "American empire".
Russia and Germany have also urged both sides to tone down the rhetoric, while South Korea expressed appreciation for Xi and Trump's phone call Saturday.
Nearly a week ago, the UN Security Council unanimously passed fresh sanctions against Pyongyang over its weapons program, including export bans, a new punishment that could cost North Korea $1 billion a year.