Three houses were petrol-bombed in Eneerdale, south of Johannesburg in the early hours of Saturday morning, said police.
"No injuries were reported but there was some damage reported to the houses," said Major Mac Mngomezulu.
He explained that on Friday locals had marched to several houses in the area, including these three, where suspected drug dealers lived or operated from.
"They warned people at the houses to stop selling drugs," said Mngomezulu.
The houses were later petrol-bombed.
Mngomezulu said it was not immediately clear whether any of the marchers were linked to the attacks.
"We have opened cases of malicious damage to property but no arrests have been made," Mngomezulu said.
Asked about the extent of damage to the properties, Mngomezulu said windows, curtains, a lounge suite and a bedroom suite had been destroyed in fires caused by the petrol-bombs.
While there were people in the houses at the time of the attacks, all of them were able to escape unharmed.