China cautioned the United States it could take "firm counter-measures" if Washington continues to show support for pro-democracy protesters in Hong Kong.
The warning came after US President Donald Trump signed the Human Rights and Democracy Act into law.
The act mandates an annual review, to check if Hong Kong has enough autonomy to justify special status with the US.
Trump is currently seeking a deal with China, in order to end a trade war between the two countries.
"The US has been disregarding facts and distorting the truth," a Chinese foreign ministry statement said.
"It openly backed violent criminals who rampantly smashed facilities, set fire, assaulted innocent civilians, trampled on the rule of law, and jeopardised social order."
The ministry threatened "counter measures" if the US continued "going down the wrong path".