Chinese Foreign Minister Wang Yi considered the passage by the US Congress of a law supporting democracy and human rights in Hong Kong as an "incentive for violent criminals."
The purpose of this text is to "wreak havoc or even destroy Hong Kong," Wang Yi said in a statement issued by his ministry.
The Chinese Foreign Ministry spokesman also said China was ready to "react with determination" and urged US President Donald Trump to veto the legislation.
"We condemn and strongly oppose" this initiative, which "undermines the interests of China and the United States" in the semi-autonomous region of China, said Geng Shuang. "If the US continues to take the wrong action, China will surely take strong countermeasures," Geng warned.
The US Congress on Wednesday passed a resolution supporting "human rights and democracy" in Hong Kong and threatening to suspend Washington's special economic status to the former British colony, which has been the scene of anti-government demonstrations for almost six months. , increasingly violent.
The text, which undermines the trade status currently enjoyed by the Chinese Special Administrative Region, has not yet been signed by US President Donald Trump, but the White House has not threatened to veto.
The vote comes at a time when the world's two largest powers are negotiating a way out of the trade war.
"The United States is with you and will always support you," said Michael McCaul, an elected member of the Republican minority in the House of Representatives, denouncing "the brutality" of China.
No one should underestimate China's determination to safeguard its national sovereignty.
Asked about the risk of that vote damaging the talks, the Chinese spokesman said he hoped Washington would "work with the Chinese side to find solutions."
"No one should underestimate China's determination to safeguard its national sovereignty, security and development interests," Geng said.
Congress passed the resolution with 417 votes in favor and one against, after unanimous adoption by the Senate last Tuesday. The vote led China to threaten with retaliation.
The two chambers of Congress also passed a measure that would prohibit the sale of tear gas grenades, rubber bullets and other riot gear used by Hong Kong police to suppress demonstrations.