China's Foreign Ministry spokesman Zhao Lijian urged Washington on Tuesday to "stop any form of official exchanges with Taiwan,” Press TV reported.
He warned Washington to handle the island’s “issue cautiously, and refrain from sending any wrong signals to Taiwan independence forces.”
The ministry issued the statement after a delegation of three US legislatures made a stopover in Taipei, where they said Washington would donate 750,000 coronavirus vaccine doses.
Chinese Taipei accuses Beijing of trying to block the island from accessing vaccines internationally – an allegation China rejects.
Beijing has offered the island Chinese-made Sinopharm vaccines, but the government in Taipei has declined to authorize their import, expressing concern about their safety.
The US delegation’s visit to the self-ruled island caused outrage in China over the weekend. Soon after, US Secretary of State Antony Blinken added fuel to the fire by his controversial remarks about plans to begin a trade deal with Taipei.
“I know we are engaged in conversations with Taiwan, or soon will be, on some kind of framework agreement," Blinken told a congressional hearing in Washington.
"We are committed to the proposition that Taiwan must have the means to defend itself,” Blinken said, adding that Washington has “continued to provide significant equipment and sales to Taiwan for that purpose.”
The top diplomat also accused Beijing of sowing “increased aggression” against Taipei.
The island remains China's most sensitive territorial issue and a major bone of contention with Washington. China has repeatedly warned the US against any formal relations with the government in Taipei.
Beijing has sovereignty over Chinese Taipei under the "One China" policy, which is in principle recognized by almost all world countries.
But successive US administrations and other Western governments have been seeking independent relations with Chinese Taipei.
The administration of US President Joe Biden has, likewise, taken a hostile posture against China, including over Chinese Taipei.
The US has been selling weapons to, staging shows of military force around, and facilitating diplomatic contact with the self-ruled island, in violation of Chinese sovereignty and its own stated policy.
China has in response ramped up military patrols and drills near the island in recent months, asserting its sovereignty.