The federal government's Smart Traveller website says protests have become more unpredictable and are expected to continue.

"Tourist areas have been affected. There is a risk of violent confrontation between protesters and police, or criminally-linked individuals, particularly at unauthorised protests," the website says.

Foreign Minister Marise Payne said the upgraded advice was based on increasing violence in Hong Kong.

"I'm not saying don't go, we're saying monitor local media for signs of unrest, avoid protests and large gatherings because they are unpredictable," she told 2GB on Wednesday.

The advice level is now on the second rung of a four-tier scale.

Australians have also been told the risks are greater at night and on weekends.

"We've been clearly urging Australians to avoid large public gatherings in recent weeks and most certainly read the travel advice when travelling to Hong Kong," Senator Payne said.

China has warned it's "only a matter of time" before it punishes those behind two months of pro-democracy protests that have increasingly devolved into violent clashes with law enforcement.

The protests began in response to Beijing's plans to impose tough laws in the semi-autonomous state that would have allowed it to extradite Hong Kong residents to the mainland.

"We would like to make it clear to the very small group of unscrupulous and violent criminals and the dirty forces behind them: those who play with fire will perish by it," Yang Guang, spokesman for the Chinese Cabinet's Hong Kong and Macao Affairs Office, said on Tuesday.

"Don't ever misjudge the situation and mistake our restraint for weakness."

Australian Associated Press