The USA international is under investigation after an alleged gesture to Barnsley fans on Saturday.
Shea, who is currently on loan at Barnsley, is believed to be accused of a two-fingered gesture to his own supporters after Saturday's 5-0 defeat at Huddersfield.
In a statement, Barnsley FC have said:
"As a Club, we do not condone any provocative actions from any of its employees and would like to further apologise for any offence caused.
"In relation to an alleged incident concerning Brek Shea: the matter is currently under investigation and a further statement will be made upon Brek's return from international duty."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball