"We strongly condemn and firmly oppose the passage of relevant Hong Kong related bills", Chinese Foreign Ministry spokesman Geng Shuang said, noting that Beijing was ready to take measures to "resolutely fight back".
The House voted for two bills, supporting the Hong Kong protesters by a 417-1 margin on Wednesday after they were approved unanimously by the Senate a day prior.
The news of the decision comes amid another escalation of tensions in the city, as mass rallies gathered around Hong Kong Polytechnic University, with anti-riot police threatening to use "live rounds" in retaliation to violent protesters holed up in the besieged facility.
In the meantime, the National People's Congress (NPC) of China and Hong Kong's High Court have clashed, after judges ruled the city's face mask ban was unconstitutional.
While the High Court stated the prohibition on wearing masks during demonstrations to be "incompatible with the Basic Law", Beijing cast doubt on the authority of the judges to make such a decision in the first place.
Massive protests and clashes with police began in Hong Kong in June over a controversial bill that would've allowed criminal suspects to be extradited to mainland China.
The legislation was suspended and then finally withdrawn in October, but the rallies continued, as numerous residents demanded that charges against previously detained protesters be dropped and alleged violations by the police during the unrest be investigated.
