Speaking at a press-conference, spokesman for China's Taiwan Affairs Office An Fengshan expressed official opposition to any military deals between Taiwan and the US, highlighting that Taiwan is an internal matter.
"What I want to stress and point out is that any relying on foreigners to build oneself up or plots to harm national sovereignty and territorial integrity will be opposed by the entire Chinese nation, and cannot succeed," An said.
China's warning comes following the escalation of tensions between Beijing and Taipei that were sparked by the US Congress's decision to adopt the National Defense Authorization Act in September.
The move was highly criticized in mainland China, which considers Taiwan to be a rogue province and has consistently called it as "the most sensitive issue" in its relationships with the United States.
The passing of the Act even prompted Li Kexin, a senior Chinese diplomat in Washington to issue a stern warning, stating that if US Navy ships enter Taiwan then China will activate its Anti-Secession Law, which authorizes the use of force to bring the wayward republic under control.
"The day that a US Navy vessel arrives in Kaohsiung [Taiwan's main port] is the day that our People's Liberation Army unifies Taiwan with military force," Li said at an embassy event last Friday.
Formally, the People's Republic of China and Taiwan, officially known as the Republic of China, remain a single country, as each considers the other as "renegade provinces."
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The Trump Administration had earlier agreed to honor the so-called "One China" policy.
Beijing suspects that Taiwan President Tsai Ing-wen, who leads the pro-independence Democratic Progressive Party, may call for a full-fledged referendum next year.
The potential deployment of the US Navy ships in Taiwan may, therefore, be seen as Tsai's attempts to provide physical security for the referendum that will sever Taipei from China.
