Trump will make an official visit to China later this year.
The Chinese foreign ministry said Xi urged Trump to avoid "words and deeds" that would "exacerbate" the already tense situation and to seek a political settlement.
Russian foreign minister Sergei Lavrov said on Friday "the risks are very high" of war between the USA and North Korea.
He also issued a warning to North Korea on Friday, saying that the United States military is "locked and loaded" to deal with any provocation from Pyongyang.
Trump has doubled down on his statements on a daily basis since then.
He began with a morning tweet: "Military solutions are now fully in place, locked and loaded, should North Korea act unwisely".
"Sound dialogue is not possible with such a guy bereft of reason and only absolute force can work on him", a report by the North's state-run KCNA news agency said of Trump.
Asked Friday if the US was going to war, Trump told reporters at his New Jersey golf resort, "I think you know the answer to that". "We think that lots of good things could happen and we also could have a bad solution".
The latest war of words between Trump and the North - ruled by young leader Kim Jong-Un - unnerved many in the South, even though it has become largely used to hostile rhetoric from its neighbour.
Relations between Washington and Pyongyang have been tense for months, in the wake of the North's repeated missile tests, including two successful intercontinental ballistic missile (ICBM) test launches in July that are believed to have brought much of the United States mainland within range.
The state-run KCNA news agency has previously accused the U.S. president of driving the region "to the brink of nuclear war". "North Koreans are not suicidal".
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Some countries have sounded the alarm over the provocative exchange and have, like China, called for calm.
In the U.S., support for Trump's tough talk on North Korea broke down along party lines.
German Chancellor Angela Merkel also called for restraint, saying that "escalating the rhetoric is the wrong answer". Speaking shortly after a National Security Council meeting, Trump told reporters his previous "fire and fury" remarks had not been "tough enough". The Chinese government has worked to prevent a unified Korean state allied to the United States, going all the way back to the 1950-53 Korean War that saw hundreds of thousands of Chinese soldiers die.
While backing Trump's tough talk, US officials including National Security Adviser H.R. McMaster played down the risk on Sunday of the rhetoric escalating into conflict.
The US is now pursuing talks through diplomatic backchannels, however Panetta said he's is concerned about the possibility of a "miscalculation".
Countries in the region, however, are not taking any chances.
The first Patriot Advanced Capability 3 (PAC-3) system was installed at the Ground Self-Defense Force Kochi base in Konan, Kochi Prefecture, on August 12 with the aim of intercepting North Korean missiles that stray into Japanese territory from the intended target, Guam.
Russian Federation boosted its air-defense systems in the far east.
Meanwhile, Trump was blamed for inciting chaos in the US government and making an # of himself, as it is now the national sport of Canada and some other countries to pretend is occurring every day.
The US has not taken any public steps to prepare for hostilities such as evacuating Americans from Seoul, which is within range of North Korean artillery, or moving ships, aircraft or troops into position for an imminent response.
Chinese President Xi Jinping, seen in this July 28, 2017 photo in Beijing, spoke to President Trump via phone on Friday.
Trump had been expected to order a so-called Section 301 investigation under the 1974 Trade Act earlier this month, but action had been postponed as the White House pressed for China's cooperation in reining in North Korea's nuclear program.
When asked by a reporter Friday about reports of back-channel diplomacy, U.S. Deputy Assistant Secretary of State Patrick Murphy said he didn't "have anything to comment" but added, "Now is not the opportunity for dialogue because we have not seen North Korea's willingness to address. fundamental problems" that include the development of missile and nuclear programs "in defiance of the global community".