They used burning tyres to barricade the road near the Pretoria/Sun City offramp, Lieutenant Colonel Lesego Metsi said in a statement.
He advised motorists to use alternative routes.
"We are trying to reopen the road, but it's difficult to control traffic and the masses at the same time."
In recent protests at Bapong and Bethanie, residents demanded jobs and local development from mining companies in the area.
"This is the third protest action in two consecutive weeks in the province where the police had to divert resources earmarked for fighting crime," Metsi said.
There had been no arrests, injuries or damages during the protest on Friday.