Dynamo's Clark apologizes for gay slur
Clark can be heard calling the boy a profane, derogatory name in footage of the incident filmed from the crowd that was later uploaded to YouTube.
The slur also was audible on the NBC Sports Network broadcast, The Seattle Times reported.
The youngster had opted to roll the ball to Clark's feet rather than pitch it to his hands when it went out of play for a Houston throw in the seventh minute at CenturyLink Field.
Clark later tweeted, "I'd like to offer a sincere apology to everyone who watched the game, especially the ball boy for whom I used awful language towards. I didn't mean to disrespect anyone and am sorry for letting my emotions get the best of me. It's not who I am, and it won't happen again."
Clark also responded to a group advocating gay rights in soccer, saying, "I'm very sorry for my actions [Friday night], and I would love for you to consider me a #soccerally moving forward."