Chinese actress Crystal Liu, also known as Liu Yifei, allegedly posted a message on social media platform Weibo which translates as: "I support the Hong Kong police. You can all beat me up now.”
She added in English: “What a shame for Hong Kong."
The post comes amid heightened tensions in the former British colony, where pro-democracy demonstrators have clashed with local police.
The protests were originally sparked by controversial extradition proposals, but have continued as rights groups and the UN have accused the police of a heavy handed response.
Ms Liu’s comments provoked fierce criticism in the west, and the hastag #BoycottMulan soon began trending online.
Critics accused the actress, now a US citizen, of supporting police brutality and denying Hong Kong citizens the rights she enjoys in her adopted country.
She is not the only star who has been criticised for their stance on the protests.
Martial artist Jackie Chan, who was born in Hong Kong, reportedly told Chinese TV CCTV that the events were "sad and depressing".
He added: "I have visited many countries and I can say our country has been rapidly developing in recent years. I feel pride in being Chinese wherever I go and the 'five-starred Red Flag' is respected everywhere around the world."
He was accused of failing to support pro-democracy protesters.
Demonstrators first took to the streets in June after the Hong Kong government put forward controversial extradition proposals that would have allowed some suspects to be sent to mainland China for trials.
This led to fears of Hong Kong's independent legal system being bypassed, with people being pulled into China's legal system - which can involve television confessions and a lack of judicial safeguards seen in Hong Kong and the UK.
The government suspended the planned legislation although protesters have pressed on with broader calls for it to be scrapped entirely along with demands for democratic reforms.
Disney has been contacted for comment. Mulan, a live-action reimagining of the 1998 animated film, is set to arrive in March next year.