Olympic boxer Terrell Gausha ashamed to sport the american flag on his boxing trunks!!!!

U.S. Olympic boxer Terrell Gausha is so disgusted over the George Zimmerman verdict ... he's vowing to never sport the red, white and blue again.

Gausha -- who boxed in the 2012 London Summer Games -- started wearing the American flag on his boxing trunks after his Olympic run ... but tells TMZ he's done with that now in the wake of Zimmerman's acquittal in the killing of Trayvon Martin.

Terrell adds, "How can I wear my stars and stripes proudly in a country where they make a big deal out of Mike Vick fighting dogs; but not a young innocent black male's life."

Gausha added, "When I represented my country in the Olympics I was proud to wear my flag. I even wore it on my head on the way to the ring. What happened this weekend was a slap in the face."

Gausha has turned pro -- so he's not eligible for the U.S. team in 2016 -- but doesn't sound like he's interested ... telling us he refuses to rep a "nation with so much racism and hatred."