Pictures and video have circulated showing hundreds of people engaged in a stand-off with police in a central Shanghai shopping district.
Authorities have stoked anger among investors and homeowners with a campaign launched last month to rein in the use of commercial-zoned real estate for residential purposes.
Videos showed a crowd in excess of 1,000 people confronted by police, who erected cordons to block their march on Nanjing East Road.
"An oppressive government drives the people to rebellion. The poor masses!" said one of many outraged postings on Weibo.
"Once again, the government is doing things without considering the stance of the masses," said another.