All India Central Council of Trade Union national secretary Rajiv Dimri said their demand is reinduction of the 500 workers, who were allegedly sacked "illegally and arbitrarily, sans any inquiry.
"Police forces and bouncers, who have been stationed at the plant, should also be removed," he said.
The decision to terminate the services of 500 permanent workers was taken by MSIL after they were allegedly found to have been involved in violence inside the plant last month.
They also sought the immediate release of 155 workers who were jailed after months of labour unrest erupted in mob violence on July 18.
"All cases against the 155 arrested workers should be dropped and police officials guilty of custodial torture of arrested workers should be prosecuted," said Dimri.
They also sought a judicial enquiry into the state of implementation of labour laws in the industrial zones of Gurgaon-Manesar-Dharuhera region.