Landon Donovan said his San Diego Loyal "would not stand" for bigotry having left the pitch in protest after an alleged homophobic comment was aimed at midfielder Collin Martin, who is gay.
An opposition player from Phoenix Rising was accused of making the comment just before half-time in their second-tier USL Championship game.
Loyal players returned after the break but walked off when the referee blew his whistle, forfeiting a match they were leading 3-1 and ending their chances of reaching the play-offs.
They forfeited a match against LA Galaxy II last week after an alleged racial slur was aimed at midfielder Elijah Martin. The player accused of making the comment has since been let go by Galaxy.
Loyal players took a knee before walking off during Wednesday's second division game against Phoenix Rising.
Loyal manager and executive vice-president Donovan, who played in the Premier League for Everton, said: "We went through a really hard incident last week in the LA match and we made a vow to ourselves, to our community, to our players, to the club, to USL, that we would not stand for bigotry, homophobic slurs, things that don't belong in our game."
