Skipper Misbah-ul-Haq (26) and young batsman Umar Amin (7) were at the crease for Pakistan.
Both the sides need to win the contest to remain in hunt for the semifinals
Pakistan lost Imran Farhat (2), Mohammed Hafeez (7), Shoaib Malik (8) and Nasir Jamshed (42) as South African bowlers exploited the conditions extremely well.
Paceman Chris Morris accounted for Farhat and Hafeez. Malik was bowled by J P Duminy while Lonwabo Tsotsobe dismissed Jamshed.
Earlier, prolific batsman Hashim Amla (81) crafted a superb half-century but Pakistan rode on intermittent strikes to restrict South Africa to 234 for nine.