Shikhar Dhawan top-scored for the visitors with his 72-run knock from just 39 balls while debutant paceman Junior Dala took two wickets for the hosts.
It is India's highest score against South Africa in T20Is.
Brief Scores:
India: 203 for 5 in 20 overs. (S Dhawan 72, Manish Pandey 29 not out, Virat Kohli 26; Junior Dala 2/47, Tabraiz Shamsi 1/37).