United were ahead in the Champions League tie against the Spanish champions before the Portuguese winger was controversially sent off for a high boot on Alvaro Arbeloa.
Following the sending off, Giggs, who made his 1000th career appearance in the game, said that he tried to rouse the United crowd after becoming furious with the decision.
"I've never done that before! I think it was anger and obviously trying to get myself up," Giggs told the Daily Mail.
"I was pumped. The crowd had been brilliant all night and I wanted to get them up and was just looking for that little bit of edge where it could help us. I didn't plan it.
"I'd seen the ball go out for a dead ball and just felt that rush of adrenaline. It was one of those special nights at Old Trafford when sometimes you do things that, you don't plan. It just happens."