The statement did not specifically mention China, but comes amid simmering tension between Beijing and Washington and its allies over the disputed South China Sea.
China's foreign ministry said it strongly deplored and opposed the “irresponsible” remarks made by the three countries, urging them to “cease any form of connivance with separatist activities of Taiwan independence”.
Regarding the South China Sea, ministry spokesperson Guo Jiakun said at a press conference the nations should respect efforts by regional countries to resolve issues through dialogue and consultation, and stop “exaggerating tensions and provoking confrontation”.
Taiwan's foreign ministry welcomed the expression of concern.
It will co-operate with the US, Japan, South Korea and other like-minded partners to ensure peace and stability in the Taiwan Strait and Indo-Pacific, ministry spokesperson Hsiao Kuang-wei told reporters in Taipei.
China claims almost the entire South China Sea, overlapping the exclusive economic zones of Brunei, Indonesia, Malaysia, the Philippines and Vietnam. Unresolved disputes have festered for years over ownership of islands and features.
US secretary of state Marco Rubio, South Korean foreign minister Cho Hyun and Japanese foreign minister Iwaya Takeshi met in New York on Monday and also discussed the three countries' continued commitment to ending North Korea's nuclear programme, their joint statement said.
China, which views the democratically-governed island as its own territory, has stepped up its military activities nearby, including staging war games. Taiwan's government rejects China's territorial claims.
