The defence ministry said the drills were routine and were not targeting any specific country.
China is locked in territorial rows with several nations, and the US has recently made a series of announcements bolstering its presence in the region.
A Pentagon spokesman said the US had no problem with the naval exercises.
Captain John Kirby said that China was “entitled to exercise their military in ways they deem fit”.
China has clashed with several other nations in the South China Sea, where countries including Vietnam and the Philippines have overlapping claims.
US President Barack Obama announced last week that the US was boosting its presence in the region, and will base a full Marine task force in northern Australia.
Analysts say the US move is a direct challenge to China’s attempts to dominate the area, and is likely to bolster US allies in the South China Sea dispute.