The incident happened at King Zwelithini Stadium on September 20, with both players subsequently charged by the PSL for misconduct after Morton reacted by shoving the Malawian to the ground.
Mhango has expressed remorse on Twitter, saying: "At the end of last month, I was involved in an incident that should not have happened in the beautiful game of football. I offended Michael Morton and AmaZulu FC. I also disrespected my club, and above all, I disrespected the beautiful game of football. To all, I apologise unequivocally.
"This spitting incident should not have happened. Because of disciplinary action pending against me by both my club and the PSL, I was advised not to make any statements until such time as these processes were concluded.
"I have taken full responsibility for my actions in both disciplinary processes and now that they have been concluded, I can finally speak publicly about it.
"I have also met with Michael Morton, spoken to him about the incident and offered my heartfelt apologies to him and for provoking his reaction.
"I apologise to all that I have offended with my actions, and I pray and hope that you will all understand that whilst I was wrong, I am only human, and that you can all forgive me for my actions."