China on Wednesday rebuffed US Secretary of State John Kerry's remarks on the South China Sea issue and urged the country to be cautious in its words and deeds.

"We have noticed his remarks," said foreign ministry spokeswoman Hua Chunying at a regular press briefing in response to Kerry, who said on Tuesday that the United States would speak out when China took unilateral actions that raised the potential for conflict, Xinhua News Agency reported on Wednesday.

"We hope the relevant country will respect the efforts made by China and countries of the Association of Southeast Asian Nations (ASEAN) on the South China Sea issue, strictly abide by its commitment of not taking a position, and be cautious with its words and deeds," she said.

Kerry warned China Tuesday against imposing an Air Defense Identification Zone over the South China Sea, similar to the one it declared over disputed islands in the East China Sea.

"The (East China Sea) zone should not be implemented and China should refrain from taking similar, unilateral actions elsewhere in the region and in particular, over the South China Sea," Kerry told a news conference in Manila, AFP reported.

Hua noted China always stands for a resolution of the South China Sea issue through direct negotiations between relevant countries, and keeps smooth and effective communication with ASEAN countries on the South China Sea code of conduct.

Kerry also said on Tuesday that his country backed Japan's newly-announced re-armament plan to buy stealth fighters, drones and submarines to beef up its defense of far-flung islands amid a territorial row with China, when speaking to reporters after a meeting with his Philippine counterpart in Manila.

Hua urged the United States to be more helpful for the mutual trust between countries in the region and the peace and stability of the region.