Chinese President Xi Jinping has called for a peaceful resolution to rising tensions on the Korean peninsula.
Mr Xi called US President Donald Trump on Wednesday, as a US aircraft carrier strike group steamed towards the region.
Mr Trump, in an early morning note on Twitter, said the call with Mr Xi, just days after they met in the United States, was a "very good" discussion of the "menace of North Korea".
The call came as an influential state-run Chinese newspaper warned that the Korean peninsula was the closest it has been to a "military clash" since North Korea's first nuclear test in 2006.
The communication between the leaders underscored the sense of urgency as tensions escalate amid concern that reclusive North Korea could soon conduct a sixth nuclear test, or more missile launches, and Mr Trump's threat of unilateral action to solve the problem.
Mr Trump ordered the USS Carl Vinson aircraft carrier group to head to the Korean peninsula in an attempt to deter North Korea's nuclear and long-range missile ambitions, which it is developing in defiance of UN resolutions and sanctions.
He pressed Mr Xi to do more to curb North Korea's nuclear programme when the two leaders held their first face-to-face meeting in Florida last week.
Mr Trump said on Twitter on Tuesday that North Korea was "looking for trouble" and the United States would "solve the problem" with or without China's help.
Mr Xi stressed in their telephone call that China "is committed to the target of denuclearisation on the peninsula, safeguarding peace and stability on the peninsula, and advocates resolving problems through peaceful means", Chinese state broadcaster CCTV said.
Chinese Foreign Ministry spokesman Lu Kang, who said Mr Trump had initiated the call, urged everyone to lower the tension.
"We hope that the relevant parties do not adopt irresponsible actions. Under the current circumstances, this is very dangerous," Mr Lu told reporters.
North Korean state media warned on Tuesday of a nuclear attack on the United States at any sign of American aggression.
Officials from the North, including leader Kim Jong-un, have indicated an intercontinental ballistic missile test or something similar could be coming.
Russia has said it is worried about the possibility of a US attack on North Korea and it would raise the issue with visiting US Secretary of State Rex Tillerson.
Earlier on Wednesday, two sources in Tokyo said Japan's navy planned exercises with the Carl Vinson carrier group in a joint show of force.
Japan's Maritime Self Defence Force and the US Navy could conduct helicopter landings on each other's ships, as well as communication drills, they said.
South Korea's acting president, Hwang Kyo-ahn, has warned of "greater provocations" by North Korea and ordered the military to intensify monitoring.