Videos that said they were filmed at the factory in the central city of Zhengzhou showed thousands of people in masks facing rows of police in white protective suits with plastic riot shields.
Last month, thousands of employees walked out of the iPhone factory operated by Taiwan’s Foxconn Technology Group over complaints about unsafe working conditions following virus cases.
Foxconn denied what it said were comments online that employees with the virus lived in dormitories at the Zhengzhou factory.
“Regarding any violence, the company will continue to communicate with employees and the government to prevent similar incidents from happening again,” the company statement said.
Foxconn said earlier its Zhengzhou factory uses “closed-loop management,” which means employees live at their workplace with no outside contact.
The city government suspended access to an industrial zone that surrounds the factory, which Foxconn has said employs 200,000 people.
News reports said the ruling party had ordered “grassroots cadres” to fill in for Foxconn employees in Zhengzhou who left.