Esper, who is on an official visit to Japan, made these remarks at the start of a meeting in Tokyo with Japanese Prime Minister Shinzo Abe, with whom he discussed the escalation of tensions between Beijing and Washington, the US-Japan bilateral alliance and the latest missile tests by North Korea.
"China continues to destabilize the region. Their military aggression and calculated strategy of predatory economics violates the international rules-based order that we are trying to uphold," Japanese news agency Kyodo quoted Esper as saying.
The Pentagon chief once again lashed out at China after the US decided on Monday to designate the Asian country as a currency manipulator, thereby extending the trade conflict between the world's top two economies into the realm of currency and making the possibility of an agreement seem more remote than ever.
He also expressed concern over the recent missile tests by North Korea and said that Washington remains committed to the "complete, irreversible and verifiable denuclearization of North Korea", Efe news reported.
Esper's visit to Japan and South Korea, where he will travel on Friday, comes after Pyongyang conducted four missile launches in two weeks, tests that North Korean leader Kim Jong-un described as a "warning" to the allied countries.
He is also scheduled to meet his Japanese counterpart, Takeshi Iwaya, on Wednesday to discuss bilateral security ties as well as the alliance the two countries have with South Korea at a time when relations between Seoul and Tokyo have fallen to their lowest level in recent decades owing to a historical dispute.
The US and Japanese Defence Ministers are also expected to discuss the possibility of Japan joining the US-led initiative to form a naval mission to escort tankers in the Persian Gulf, in the current context of tensions with Iran.
( With inputs from IANS )