Bale contributed to Los Blancos' first goal which was finished by Karim Benzema, before the team went on to win 3-1.
"He [Bale] has given us titles, he's scored in finals and he has a lot of respect from us all," Casemiro said.
"He has to play. He's a great player and is very important for us."
"The Barcelona defeat doesn't change anything," Casemiro added.
"We are thinking about our football and about our matches."