China is seriously concerned about nuclear threats after North Korea said they would test missiles regularly and warned of a pre-emptive nuclear strike against the US in case they suspected an attack.
According to a report in the BBC on Wednesday, China's Foreign Ministry spokesman Lu Kang said that they opposed words or actions that could further raise tension.
Tensions have been escalating on the peninsula, with heated rhetoric from both North Korea and the US.
North Korea has accelerated its nuclear and missile tests in recent years, despite international condemnation and UN sanctions.
Its aim is to be able to put a nuclear warhead on an intercontinental ballistic missile that can reach targets around the world, including the US.
US President Donald Trump has said that will not happen, and stepped up pressure on the isolated North.
He has sent a navy strike group towards the Korean Peninsula, and the US and South Korea are moving ahead with the early deployment of a controversial missile defence system.
Despite the tension, North Korea may carry out a sixth nuclear test soon, observers say. It test-fired a missile on Sunday that exploded within seconds of launch, following a grand military parade on Saturday.
Earlier, US Vice President Mike Pence warned North Korea not to test the US, adding his country's "era of strategic patience" with Pyongyang was over.
The US military is considering shooting down the missile tests to pressure North Korea into denuclearisation, particularly if Pyongyang goes forward with a sixth nuclear test.