Chinese President Xi Jinping told his South Korean counterpart on Wednesday that Beijing is willing to help "reconciliation" between Seoul and Pyongyang, the foreign ministry said.
"China is willing to provide the necessary assistance to advance South-North reconciliation and cooperation," he told President Park Geun-Hye in a phone call, according to a statement on the ministry website.
"The South and North are compatriots, and South-North relations are important to the situation on the peninsula," the newly elevated Chinese leader said.
China is Pyongyang's sole major ally and by far its biggest trading partner, including being its primary energy supplier.
Tensions on the Korean peninsula - which has been divided since the 1950-53 Korean War - have surged since the North carried out its third nuclear test in February, following a long-range rocket launch in December.
Beijing has repeatedly urged calm and restraint and promoted dialogue, but earlier this month voted in favour of a UN resolution that stiffened sanctions against Pyongyang over the latest nuclear blast.
Xi was named China's president last week and has been holding his first discussions with foreign counterparts, while Park was inaugurated as South Korea's first female president last month.