Zhang Xiaoming, one of the most senior Chinese officials overseeing Hong Kong affairs, made the comments during a meeting in the southern Chinese city of Shenzhen.
Zhang was holding a forum that included Hong Kong delegates to China's parliament, the National People's Congress and China's main consultative body, the CPPCC, to discuss the political crisis in the territory.
Hong Kong has faced months of sometimes violent protests that began with opposition to a now-suspended extradition law, which would have allowed suspects to be tried in mainland courts controlled by the Communist Party.
But the protests have broadened into a backlash against the Hong Kong government, fueled by many residents' fears of eroding freedoms under the tightening control of China's Communist Party leaders in Beijing.
Hong Kong lawyers dressed in black are set to march in silence on Wednesday to call on the government to safeguard the independence of the city's justice department.
Protesters plan to surround Hong Kong's Revenue Tower on Wednesday, after police late on Tuesday fired tear gas to disperse protesters in Sham Shui Po, one of the city's poorest districts.
Hong Kong's lawyers fear the Department of Justice's prosecutions of arrested protesters is taking on an increasingly political slant after 44 protesters were charged with rioting, an offense which carries a 10-year jail term.
Last week a group of unnamed government prosecutors published an open letter accusing Justice Chief Teresa Cheng of putting politics above legal principles.
Hong Kong's mini-constitution, known as the Basic Law, states that the city's Department of Justice "shall control criminal prosecutions, free from any interference."
Hong Kong was guaranteed freedoms not granted in mainland China, including an independent judiciary, under a "one country, two systems" formula, when Britain handed it back to China in 1997. But many residents see the now suspended extradition bill as part of a relentless march toward mainland control.
Protesters are demanding a complete withdrawal of the bill, an independent inquiry into the crisis, an investigation into what they say is excessive use of force by police, and for Hong Kong's leader Carrie Lam to step down.
In China's sharpest rebuke yet of the protesters, the government on Tuesday warned them not to "play with fire," saying they were pushing Hong Kong into a "dangerous abyss" and called on Hong Kong citizens to protect their homeland.
Global Times, a Chinese tabloid published by the ruling Communist Party's People's Daily, showed a video on its official Twitter feed of thousands of police officers taking part in an anti-riot training drill in the southern Chinese city of Shenzhen which borders Hong Kong.
The video showed officers in helmets and shields clashing with people in black shirts and yellow construction hats, similar to the unofficial uniform of protesters in Hong Kong.Police have arrested more than 500 people in the protests so far and fired nearly 2,000 rounds of tear gas.