Hong Lei, a spokesman for the Chinese Ministry of Foreign Affairs, said the American moves "will only intensify antagonism" with Pyongyang without resolving the issue, CNN reported.
U.S. Defense Secretary Chuck Hagel announced Friday additional ground-based missile systems would be deployed to the West Coast to defend against any attacks by North Korean missiles.
The United Nations last month increased sanctions against North Korea after it conducted a third nuclear test. Pyongyang subsequently threatened a pre-emptive nuclear strike against South Korea and the United States.
Hong, speaking at a news briefing in Beijing, said China believes the American missile buildup "matters to global strategic balance and regional stability. It also matters to strategic trust between relevant countries."