About 500 people blocked a road with burning tyres near Cape Town International Airport on Friday morning, the city's disaster risk management centre said.
Spokesperson Wilfred Solomons-Johannes said people started gathering from 4am on the N2 highway, throwing stones at passing vehicles.
He said police fired rubber bullets to disperse the crowd.
The highway was closed in both directions, between the Mew Way and Duynefontein offramps.
Motorists were being diverted onto the R300.
The police were not immediately available for comment.