Chinese Ambassador to Japan Cheng Yonghua has lashed out at Japan and the United States, criticizing the two countries' agreement to further boost their bilateral security alliance as a move to position Beijing as an "enemy."

"It sounds as if Japan and the United States are purposely taking China as their enemy and saying 'Let's join hands and go at China,' " Cheng told reporters in the Chinese capital Friday.

The ambassador also described the strengthening of the Japan-U.S. alliance as "clearly a Cold War mindset," adding that it goes against Tokyo's promise to improve relations with China.

"Frankly speaking, I am dissatisfied with what the Japanese side has been doing since January," Cheng said with regards to Sino-Japanese ties.

The envoy's remarks came after senior security advisers to Prime Minister Shinzo Abe and U.S. President Donald Trump agreed earlier this week to closely coordinate in further boosting the bilateral security alliance.

In their meeting in Washington, Shotaro Yachi, head of the secretariat of the National Security Council, and H.R. McMaster, Trump's national security adviser, also exchanged views on security challenges in the Asia-Pacific region, including China's assertive territorial claims in the East and South China seas, according to a Japanese official.