The warning on Wednesday came as Tsai was due to depart for a trip to Guatemala and Belize, which will see her transit through New York and California in the US.
While not officially confirmed, she is expected to meet McCarthy while in California, at the end of her 10-day trip.
China, which claims democratically-ruled Taiwan as its own territory, has repeatedly warned US officials not to meet Tsai, viewing it as support for the island’s desire to be seen as a separate country.
Beijing staged war games around Taiwan last August when then-US House Speaker Nancy Pelosi visited Taipei. Taiwan’s armed forces have said they are keeping watch for any Chinese moves when Tsai is abroad.
Zhu Fenglian, spokesperson of China’s Taiwan Affairs Office, told reporters in Beijing that Tsai’s “transits” of the US were not just her waiting at the airport or hotel, but for her to meet US officials and legislators.
“If she has contact with US House Speaker McCarthy, it will be another provocation that seriously violates the one-China principle, harms China’s sovereignty and territorial integrity, and destroys peace and stability in the Taiwan Strait,” she said.
“We firmly oppose this and will definitely take measures to resolutely fight back,” Zhu added, without giving details.
Taiwanese presidents routinely pass through the US while visiting diplomatic allies in Latin America, the Caribbean and the Pacific, which, although not official visits, are often used by both sides for high-level meetings.
The Taiwanese president is expected to give a speech in New York hosted by the Hudson Institute, a conservative US think tank, on March 30 en route to Latin America and then again at the Ronald Reagan Presidential Library in California on her return to Asia in April.
She has visited the US four times since first taking office in 2016, during which time she met with Republican senators Marco Rubio and Ted Cruz, with each trip becoming more formal than the last.
“Such visits are a reaffirmation of US support for Taiwan at a time when critics of the Tsai administration – and the CCP [Chinese Communist Party] – strive to sow doubt about the reliability and commitment of the US as a partner to Taiwan,” J Michael Cole, a Taipei-based adviser with the International Republican Institute, told Al Jazeera.