Signs of social instability could potentially harm South Africa's image and investor sentiment, undoing the gains of hosting a successful soccer World Cup tournament that ended on Sunday.
Police said the situation in the Western Cape province was tense but there have not been injuries so far.
"There were two shacks that were burned in separate areas and there's been sporadic incidents of looting and threats have been made on foreign nationals," said Western Cape police spokesman Frederick van Wyk.
"Police have responded. At this moment there is a heavy police contingent (in several areas) which also includes Metro police and SANDF (South African National Defense Force)," he added.
The biggest economy in Africa has attracted millions of workers from across the continent and further afield, but their presence is not always welcomed by those locals who compete with them for scarce jobs and resources.
Two years ago more than 60 people were killed during anti-foreigner attacks.
Police in Gauteng said there had not been incidents against foreigners in the economic hub of South Africa.
