Gamula was speaking at a post-match press conference on Friday after his side’s 1-0 victory over Ural in the Russian Premier League.
The coach was asked by local media whether Rostov would sign Cameroon defender Benoit Angbwa, who has apparently been linked with the club.
Gamula allegedly responded by saying that he won’t sign black players and claimed Ebola has spread to the club after five of his players reportedly fell ill.
“We have enough dark-skinned players, we've got six of the things,” he is quoted as saying.
Xulu, whose move from Mamelodi Sundowns to Rostov was confirmed in September 2012, was angered by the coach’s comments and he has subsequently stopped training with the club until he has a meeting with management, which is expected to happen today.
Gamula claims he was joking.
There are often reports relating to racism in Russia’s football circles and players like Hulk of Brazil have in the past been subjected to racist taunts.
Russia will host the 2018 FIFA World Cup.