"The Chinese side is working to properly manage situation in the relevant waters," Chinese Foreign Ministry spokesperson Hua Chunying said in a statement.
"We strongly hope that the Japanese side will honour its principled agreement with us, deal with the current situation with a cool head instead of taking actions that may raise tension or make things complicated, and make constructive efforts for stability in relevant waters together with us," she said.
"China's position on the issue of Diaoyu Dao is clear and consistent, that is, Diaoyu Dao and its affiliated islands is an inherent part of China's territory, and China has indisputable sovereignty over them and the adjacent waters," Hua said.
Reports Tokyo quoted Japanese officials as saying over Chinese coast guard ships along with 230 fishing boats entered the waters of the disputed islands.
