Chinese President Xi Jinping offered North Korean leader Kim Jong Un - in a letter - cooperation to "accelerate peace" in the world, the official North Korean News Agency reported.
The move comes at a time when tensions are at their peak on the Korean peninsula after a record series of missile tests by Pyongyang, while Seoul, Washington and Tokyo have boosted military cooperation between them.
Pyongyang launched an intercontinental ballistic missile on November 18, which landed near Japan.
Kim Jong Un threatened the United States with a nuclear response if his country was attacked.
And the Chinese president said - in a message he addressed to his North Korean counterpart in response to a letter from Kim, who congratulated him on his reappointment at the head of the Chinese Communist Party and the state last October - that the world, era and history are changing in an unprecedented way.
"Faced with this new situation, I am ready to contribute positively with you to accelerating peace, stability, development and prosperity in the region and the rest of the world," said the Chinese president.
China is North Korea's most important ally and trading partner, which is under tough sanctions from the United Nations over its nuclear and missile programmes.
After a meeting of the UN Security Council last Monday, China and Russia refused to join the other 13 council members - including the United States, India, France and Britain - that condemned Pyongyang's launch of intercontinental ballistic missiles on November 18.
And last May, Beijing and Moscow vetoed a draft resolution submitted by Washington to strengthen sanctions against North Korea.
During an interview last week on the sidelines of the G20 summit in Bali, US President Joe Biden asked Xi Jinping to tell North Korea "clearly" that it should not conduct a new nuclear test that Seoul and Washington believe he is preparing.
An American official said afterward that our diplomacy would certainly seek to get China to join the countries that publicly condemn that day, and use its influence to persuade North Korea.