Beijing warned Tokyo on Monday that reckless actions would be met with a "resolute response", a day after Japan's Prime Minister Sanae Takaichi, who is viewed as critical of China, won a landslide election.
China and Japan have been locked in a spat over comments by Takaichi in November that Tokyo could intervene militarily in any attack on self-ruled Taiwan.
China claims the democratic island as part of its territory and has not ruled out force to annex it.
A spokesman for China's foreign ministry on Monday urged Japan to retract the comments and warned of consequences for any rash actions.
"If the far-right forces in Japan misjudge the situation and act recklessly, they will inevitably face resistance from the Japanese people and a resolute response from the international community," spokesman Lin Jian told a regular news conference.
"We once again urge the Japanese side to retract the erroneous remarks made by Takaichi regarding Taiwan and demonstrate basic sincerity in safeguarding the political foundation of China-Japan relations, through concrete actions," he said.
In the wake of Takaichi's comments in November, China has discouraged its nationals from travelling to Japan, citing deteriorating public security and criminal acts against Chinese nationals in the country.
In the latest escalation of the row in December, Chinese military aircraft locked radar onto Japanese jets, prompting Tokyo to summon Beijing's ambassador.
Beijing also reportedly choked off exports to Japan of rare-earth products crucial for making everything from electric cars to missiles.
And last month, two popular pandas departed Tokyo for China, leaving Japan without any of the beloved bears for the first time in 50 years.
