The 28-year-old defender was given his marching orders just before the hour mark for kicking Neymar after bringing the Brazilian forward down.
Barcelona went on to take advantage of their numerical superiority and scored the winner in the 75th minute through Cesc Fabregas.
"I'm not convinced it's a red card," BBC Sport quotes him as saying. "If there's any contact it's very minimal. It changed the game.
"It's hard enough playing against Barcelona with 11 men, never mind 10 men. Neymar has a reputation in the game. Sometimes he exaggerates things a little bit."
The other match in Group H ended in a 1-1 draw between Ajax and AC Milan in Amsterdam.