"It is the internal affair of the DPRK," foreign ministry spokesman Hong Lei told reporters at a regular briefing, using the official name for the North.
"As a friendly neighbour of the DPRK we hope to see national stability, economic development and people's happiness in the DPRK.
"China will stay committed to promoting the traditionally friendly relationship of cooperation with the DPRK."
China is North Korea's sole major ally and key economic benefactor, but has grown increasingly frustrated with its pursuit of a nuclear deterrent.