A source familiar with the situation in Zhengzhou said production at the plant was unaffected by the worker unrest and output remained "normal".
It makes most of the phones at the Zhengzhou plant, though it has other smaller production sites in India and southern China.
Shares of Foxconn have slipped 2% since the unrest emerged in late October.
Before the unrest, the Zhengzhou plant employed some 200,000 people.
To retain staff and lure more workers Foxconn has had to offer bonuses and higher salaries.