The N7 heading towards Malmesbury has been closed for traffic at the Plattekloof Road intersection due to protest action, Western Cape Traffic Chief Kenny Africa said on Sunday.
Africa said people were burning tyres on the N7 near Dunoon.
It was not immediately clear what people were protesting about.
Road-users were urged to be vigilant on the roads if travelling near the area.
"Please use alternative routes," Africa added.