Opting to bowl, India rode on some disciplined bowling with pace duo of Bhuvneshwar Kumar (2/23) and Jasprit Bumrah (2/28) taking two wickets each.
R Ashwin (1/43), Hardik Pandya (1/52) and Ravindra Jadeja (1/39) -- all claimed one wicket each as South Africa suffered a collapse after posting 115 for one at one stage.
Opener Quinton de Kock was the highest scorer at 53 for South Africa.
The winner of this game will qualify for the semifinal from Group B.