Gamula’s comment came when asked by journalists if the club had signed Cameroon defender Benoit Angbwa.
The 54-year-old reportedly said after Rostov’s 1-0 win over Ural Yekaterinburg on Friday: “We already have six black players, do you want me to get a seventh? Angbwa just lives here, we will not be buying him.”
According to Xulu’s agent Paul Mitchell, the 22-year-old is unhappy about the comments and has also not been paid for four months and will seek to leave.
“The player has not quit, but is seeking a meeting with the club president and is obviously very unhappy,” Mitchell said. “He is also unhappy that he has not been paid in four months and will be potentially using that fact and this incident to force a move in January.”
Gamula said his remark had been a private joke and that the British press had misinterpreted it.
“I immediately told the journalist that my remarks were between him and me and it was a joke. He took the quote and published it,” he said in an interview to Sport Express.
“I will say it again — it was a joke. I have a great relationship with all the teams dark skinned players. The British press just doesn’t understand Russian humour.”
Rostov spokesman Timur Ivanov said Xulu had refused to train.
“Xulu said that he would not train until the head coach apologized to all of the dark skinned footballers,” said Ivanov.
“Gamula personally said sorry to each of the players in question and they all shook hands with him. The dispute is over and everyone went to train. In terms of Xulu not being paid, I don not have any information regarding this issue.”
Xulu moved to Rostov in September 2012 from Mamelodi Sundowns and helped the team win the Russian Cup last season.
(Reporting By Dmitriy Rogovitskiy; editing by Martyn Herman)