Lazio's Loum Tchaouna substituted after being racially abused at Twente
Frenchman Tchaouna was clearly incensed before being taken off in the 89th minute and imitated someone making monkey noises when explaining to the bench what had upset him.
Baroni said he was preparing to substitute Pedro but decided to take off Tchaouna after being unable to calm the winger, who joined Lazio from Salernitana in July.
"The howling at Tchaouna? Unfortunately I confirm that the player perceived this," Baroni told Sky Sport Italia.
"It's a subject I don't want to expound on now, we tried to calm him down and then I substituted him because he was no longer in the emotional condition to continue. But I think the fourth official saw what happened."
UEFA did not immediately respond to a request for comment from Reuters about the abuse of Tchaouna sent outside normal business hours.
Lazio are one of a string of clubs sanctioned by UEFA for the racist behaviour of their supporters in European competition this season.
The Serie A club were fined 45,000 euros ($49,230) and will be forced to close two sections of their stadium for their next Europa League home game.