Labor Minister Mildred Oliphant issued a warning to striking workers on Wednesday, as violence was reported during motor workers' strike.
Oliphant condemned the violence in the on-going motor industry strike, and called on concerned parties to speed up negotiations, the minister said in a statement.
"This undermines genuine workers' demands and peaceful collective bargaining. The trade union leadership has a responsibility to call upon their members to exercise discipline during the protest action," the statement said.
South Africa's petrol attendants and vehicle mechanics from car fixing and automobile parts industry have been on strike for over two weeks. Striking workers demand a 30-rand (about 3 U.S. dollars) rise on their hourly salary, and monthly salary above 6,000 by 2016.
There have been reports that some striking workers were intimidating and assaulting customers, non-striking members and replacement employees.
Talks remained deadlocked between the National Union of Metalworkers of South Africa (NUMSA), organizer of the strike, and the Fuel Retailers Association (FRA).
FRA spokesman Reggie Sibiya said talks will resume on Thursday in an attempt to break the deadlock.
The strike gave a powerful blow to the country's auto industry which is still struggling to recover from a three-week strike just ended on Monday.
If the strike action in the component industry continued, the damage to the automotive industry would be immeasurable and would take years to recover, the National Association of Automobile Manufacturers of South Africa (NAAMSA) warned.