China said the United States must refrain from "stirring up trouble" or taking sides on the South China Sea issue, after Secretary of State Antony Blinken said a security deal with the Manila extended to attacks on the Philippine coast guard.

Blinken called the U.S. security commitment with the Philippines "ironclad," and said China's actions in the South China Sea had triggered a wider international reaction.

The Chinese embassy in Philippines said in a statement on Wednesday that Chinese activities in the South China Sea were "legitimate and lawful," adding that Blinken's remarks "ignore the facts, baselessly accuse China."

It also said Blinken has again "threatened China with the so-called U.S.-Philippine Mutual Defense Treaty obligations," which China firmly opposed.

The Philippines and United States are bound by a 1951 Mutual Defense Treaty by which they must support each other if there is an attack. Philippine President Ferdinand Marcos Jr last year pushed Washington to make clear the extent of that security commitment.

Blinken said Tuesday the deal extended to armed attacks on the Philippine armed forces, public vessels and aircraft, and its coast guard.

China has said the United States threatens peace and stability in the South China Sea, is not a party to issues there, and has no right to intervene in maritime issues between it and the Philippines.

"The U.S. keeps saying that it wants to safeguard freedom of navigation in the South China Sea, but in fact it wants to guarantee the freedom of navigation of U.S. warships. The fact that U.S. warships and planes traveled thousands of miles to China's doorstep to flaunt their might and provoke trouble is an out-and-out hegemonic activity," the Chinese embassy said.