Oxford United winger Sam Deering has been fined and warned about his conduct after making a racist comment on the social networking website Facebook.
The club said the 17-year-old had apologised for the remark about nurses who are treating him for a broken leg.
In a club statement Oxford chairman Kelvin Thomas said: "We take this issue very seriously.
"I have spoken to Sam personally and he has been made aware that we will not tolerate such comments."
Thomas added: "Knowing Sam and his background I am confident he is not a racist.
"He is already distraught about his injury and the operation, and feels terrible that this has happened.
"He is still on strong medication from his operation pinning his broken fibula but he sincerely apologises to anyone offended by these comments and also to the supporters, management and his fellow players at Oxford United."
Deering, who has been a revelation since breaking into United's first team, suffered a broken leg during Oxford's 2-1 defeat at Salisbury on Boxing Day.
Thomas said he had reminded the teenager about his responsibilities and was confident this would be the end of the matter.
"He must understand he is a role model and even his throwaway comments have an impact on people's lives."