"The remarks have distorted the truth, condoned the offenders, flagrantly interfered with Hong Kong affairs, which are China's internal affairs ... We deplore and firmly oppose such comments," the office's spokesperson said.
The spokesperson added that China was "rock-firm" in upholding national sovereignty, security and the stability of Hong Kong.
On Friday, Hong Kong police arrested several activists, some of whom were later released on bail. Following the arrests, two US senators, Chuck Schumer and Jim McGovern, slammed Beijing for its actions and called on Chinese President Xi Jinping to release all of the protesters.
The mass protests in Hong Kong initially started in early June as a reaction to proposed amendments to the city's extradition laws but over the months have grown into a full-blown opposition movement against Beijing’s control over the city’s internal affairs.
In mid-August, protesters occupied the Hong Kong International airport. The peaceful sit-in rally escalated into fierce clashes with some Chinese police officers who were reported injured.
Beijing condemned what it described as violent actions of the protesters, calling them "near-terrorist acts".
Chinese Foreign Minister Wang Yi called the situation in Hong Kong amid recent massive protests the most serious since the region's return to China in 1997.