Protesters have circulated plans on social media to mark Guy Fawkes Day on Tuesday by putting on now banned face masks in areas around Hong Kong.
Many people taking to the streets in recent weeks have worn the white, smiling Guy Fawkes masks made popular by anti-establishment hackers and by the film "V for Vendetta".
The masks have also become common at protests globally, including in Britain and across the United States.
Hong Kong's embattled leader Carrie Lam invoked colonial-era emergency powers last month for the first time in more than 50 years, banning face masks in a move to quell the protests.
Protesters have largely ignored the ruling and worn masks.
The protests have divided Hong Kong and undermined its economy, with the police coming in for particular scrutiny.
"Civil servants are ashamed of the crimes committed by the Hong Kong police force and the dictatorship of the Hong Kong government," said the Citizens' Press Conference, a pro-democracy group that plans a discussion on the clashes later on Monday.
Chinese state media called on Monday for a tougher line against the protesters who vandalised state-run Xinhua news agency and other buildings, saying the violence damaged the city's rule of law.
Protesters smashed doors and windows and threw petrol bombs at Xinhua's office on Saturday in some of the worst violence in weeks. They also set fire to metro stations and vandalised buildings, including an outlet of U.S. coffee chain Starbucks.
The city's Foreign Correspondents' Club expressed grave concern at the attack on Xinhua, stating that news organisations and journalists must be able to work in Hong Kong free from fear of attack and intimidation.
Mainland businesses, including banks or companies seen as supportive of China's ruling Communist Party, have been targeted by protesters angered by China's perceived meddling since Hong Kong returned to Chinese rule in 1997.
Police condemned the "rioters' violent and vandalistic acts" and vowed measures to uphold public safety.
Tear gas accidentally aimed at a fire truck on Saturday had been intended to disperse rioters, police said.
"There was misunderstanding in the verbal communication between both sides," they said on Monday. "The matter was tackled and resolved at the scene."
