The International Cricket Council announced on Sunday that Philander had been found guilty of a level one offence for "using language, actions or gestures which disparage or which could provoke an aggressive reaction from a batter upon his/her dismissal in an international match."
Buttler was fined 15 percent of his match fee after the second Test in Cape Town where he was caught on camera swearing at Philander.
Philander announced last year that he would be retiring from international cricket after the series against England.
Philander's final Test was further spoiled when he limped off the field with what appeared to be a hamstring injury after bowling just nine balls in England's second innings on Sunday.