Protestors say the management have so far refused to give in to their demands.
A spokesman for Freeport said the company was “working diligently with the union and employee leadership to resolve this work stoppage.
Ramdani Sirait said the protest had not affected production but urged staff to return to work while the “issue is being resolved to avoid impacts to employees and the company”.
Hundreds of police officers have been deployed to secure the mining area and to prevent the protest from turning violent.
The Freeport mine sits on some of the world's richest gold reserves and the US company's local subsidiary is the largest single taxpayer to the Indonesian government.
Papua, which is a resource-rich region on the western end of New Guinea island, has
been the site of a low-level separatist insurgency since its incorporation into Indonesia in the 1960s.