Spokesman Lu Kang said Sunday that the "one China" policy is "non-negotiable." Since recognizing Beijing in 1979, Washington has maintained only unofficial ties with Taiwan, the self-governing island that Beijing considers its territory — a status quo that Trump has repeatedly threatened to upend since winning the November election.
"The government of the People's Republic of China is the only legitimate government representing China," Lu said in a statement. "That is the fact acknowledged by the international community and no one can change."
Trump told The Wall Street Journal in an interview published Friday that "everything is under negotiation, including 'one China.'"
The interview is the latest indication Trump that he will shake up the U.S.-China relationship, particularly on Taiwan, which China considers a core national interest.
China was already angered by Trump's Dec. 2 phone call with Taiwanese President Tsai Ing-wen, the first time an American president or president-elect has publicly spoken to Taiwan's leader in nearly four decades. Beijing considers any reference to a separate Taiwanese head of state to be a grave insult.
Trump then said in a television interview that he didn't feel "bound by a one-China policy unless we make a deal with China having to do with other things, including trade."
After attacking China repeatedly during his campaign, Trump has continued to disparage China on his Twitter account over its military build-up in disputed areas of the South China Sea, allegedly manipulating its currency to put American companies at a disadvantage, and not doing enough to curb North Korea's nuclear program. He has also announced that a new White House trade council will be led by economist Peter Navarro, a sharp critic of Chinese economic policy who wrote a book titled "Death By China."
Trump told the Journal that he would not label China a currency manipulator as soon as he takes office, though he repeated his contention that China is manipulating the yuan.
So far, Beijing has reiterated its refusal to negotiate on Taiwan and to push for positive cooperation between the two sides, though state-run media have run several strongly worded editorials attacking Trump.
Chinese political observers on Sunday said they expected Beijing's response to change once Trump is inaugurated next week.
"Trump has not taken office yet, so he is an ordinary person now," said Shen Dingli, a professor of international relations at Fudan University. "Therefore, there's no need for China to take his remarks seriously or further respond to what he said."
Tang Yonghong, a professor at Xiamen University, said that China needed to convince Trump that "if he wants to make money from the Chinese mainland, he must be a friend of China instead of being an enemy."
"I think Trump is handling international relations, including Sino-U.S. relations, with a businessman's logic," Tang said. "He wants to see how China will respond to such provocation."