"Feel disgusted to be honest."
Mr Guvamatanga said he was shocked by the treatment, saying it was his first experience with racism in Australia after living in Zimbabwe and then living in England for 17 years.
"Not once did I experience racism [in those places]," he said.
He said his experiences in the army and tough periods growing up in Africa and moving away from Africa still hadn't prepared him for what he encountered.
Mr Guvamatanga said he tried to communicate with the bouncer that he and his friends were quietly waiting in line like everyone else, to which a staff member replied: "People like you tend to cause trouble".
The Adelaide Advertiser reports that a representative from the Signature Lounge nightclub contacted Mr Guvamatanga to apologise.
In a message sent on Facebook, Shaine Iglesias attempted to defend the nightclub's treatment of patrons who had darker skin.
The message allegedly claimed the club was the "most multicultural background (venue) on Hindley St", according to the message supplied by Mr Guvamatanga.
"We sincerely apologise about your bad experience. I would like to personally look after you and your friends ... no one should be able to have felt that kind of way."
The message also said it had plenty of patrons from different cultural backgrounds. "[The] majority of our crowd is of Aboriginal heritage".
Mr Iglesias has since deleted his Facebook account.
The South Australian Equal Opportunity has urged Mr Guvamatanga to file a complaint of unlawful discrimination on the basis of race.
If the complaint is found to be covered under the state's equal opportunity law, a conciliation conference can be facilitated to resolve the issue and if no agreement is reached, the complaint can be referred to the South Australian Employment Tribunal.
SBS News has reached out to the Signature Lounge nightclub for comment.