Rabada was found guilty of a level two International Cricket Council (ICC) code of conduct offence of "inappropriate and deliberate physical contact with a player" after leaning with his shoulder into Australia captain Steve Smith when he dismissed him in the first innings, an ICC statement said.
The 22-year-old Rabada, who took 11 wickets to help South Africa level the series 1-1, was fined 50 percent of his match fee and given three demerit points, which took him past the tally of eight that triggers an automatic suspension.
Cricket South Africa said it was seeking legal counsel about a possible appeal that could potentially make Rabada available for the next test in Cape Town, which starts on March 22.
"I found that there was contact between Rabada and Smith, and in my judgement the contact by Rabada was inappropriate, and deliberate," match referee Jeff Crowe said in an ICC news release.
"He had the opportunity to avoid the contact and I could not see any evidence to support the argument that the contact was accidental.
"It is also disappointing that this has happened the day after the pre-match meeting I had with both teams, where the importance of respect for opponents was highlighted."
Rabada also accepted a second level one charge of "using language, actions or gestures which could provoke an aggressive reaction from a batsman upon his dismissal" in his send-off to David Warner after dismissing the Australian opener on Sunday.
Rabada received a further 15 percent deduction of his match fee and an additional demerit point.
In an increasingly acrimonious series during which Warner, Australia spinner Nathan Lyon and South Africa wicketkeeper Quinton de Kock have also been punished by the ICC, Mitchell Marsh was added to that list on Monday.
The Australia all-rounder was fined 20 percent of his match fee and handed one demerit point for a level one offence of "using language or gesture that is obscene, offensive or insulting".
He was caught on camera swearing at Rabada after being dismissed early on the fourth morning.
Rabada missed the second test against England last year having reached four demerit points.
First Published: March 12, 2018, 8:45 PM IST