Former Cosatu general secretary Zwelinzima Vavi and EFF leader Julius Malema are plotting to overthr.
Three houses were petrol-bombed in Sekhukhune, Limpopo police said on Thursday.
One of the homes belonged to a traditional healer, said Lieutenant-Colonel Mohale Ramatseba.
Residents went on the rampage on Wednesday and torched the residences.
The windscreen of a police vehicle was also damaged by stones.
Ramatseba said the motive for the crime was not known.
It was not clear if anyone had been injured and no arrests were made.