The 29-year-old curled the ball into the top corner, beating Edwin van der Sar from the edge of the area in order to put the Spanish champions ahead by two goals and effectively out of sight.
"The goal at Wembley was the most important of my career," he is quoted as saying by AS.
"It was the best for the scenario and how important it was in terms of winning the game. It helped us draw a little closer to winning the Champions League."
Barcelona begin the defence of their La Liga crown at Malaga on Sunday, August 21.