"I think it’s funny, but the last thing you’ll ever see me do is jump up and down, saying, "These are lies!" he told US gay and lesbian magazine The Advocate .
"That would be unfair and unkind to my good friends in the gay community," added the star, who has been dating former pro wrestler Stacy Keibler for the past six months.
"I’m not going to let anyone make it seem like being gay is a bad thing.
"My private life is private, and I’m very happy in it. Who does it hurt if someone thinks I’m gay?
"I’ll be long dead and there will still be people who say I was gay."
The Descendents star's pal Brad Pitt – a supporter of gay marriage – has joked about the rumours in the past, saying he wouldn't marry until George was legally able to marry his "partner".
"He's been funny about it, because he knows that the best and most effective way to end marriage inequality is to point out the ridiculousness of it,' he says.
George's past girlfriends have included glam Italian TV presenter Elisabetta Canalis, cocktail waitress Sarah Larson and British model Lisa Snowdon.
All the news as Duchess Kate's due date draws close...