In his post-game press conference Arteta revealed that one of his substitutes had heard the comments coming from the West Stand and the visitors then made fourth official John Brooks aware.
Referee Andre Marriner was summoned to the touchline just after the half hour mark in Leeds' 4-1 Premier League defeat to the London club to be apprised of the situation.
"Unfortunately I can confirm that," said Arteta.
"It was reported to the stadium manager and it is for the authorities. It was a player on the bench, one of those heard the comments."
The Premier League has also confirmed to the YEP that the allegation involved racist abuse.