Montreal Impact winger Dominic Oduro claims fans of Costa Rican side Alajuelense were racist towards him as the Canadian side reached its first Concacaf Champions League final.
The Ghanaian, 29, set up the opener in a 4-2 second-leg defeat but the MLS team won the semi-final on away goals.
Oduro tweeted: "So sad that in this generation some fans still make monkey noises when black players are playing the game.
"Shame to all #alajuelense fans."
He later added: "Say no to racism on the field."
Regional governing body Concacaf told BBC Sport that once racist chanting was heard by officials in the 75th minute of the match, the first stage of its anti-racism protocols was immediately followed.
A Concacaf diversity officer asked for a public announcement to be made requesting the crowd to stop the abuse, and it was successful.
Oduro could play in Costa Rica again in the two-legged final as Herediano hold a 3-0 advantage over Mexican side Club America ahead of the second leg of their last-four tie.