The goalkeeper wants to focus on facing Real Sociedad before thinking about the second leg against Juventus
Juve romped to a 3-0 victory in the first leg of their quarter-final tie, Paulo Dybala scoring twice in the first half before Giorgio Chiellini added a header after the break.
Ter Stegen thinks it is best for Barca's players to discuss what went wrong internally, but acknowledged the loss had hurt.
"It was a painful night," the goalkeeper told the club's website.
"The first half especially was far from perfect. There are things we need to work on improving.
"I hope the fans will come out and support us for the second leg."
Before trying to replicate their famous comeback from the previous round against Paris Saint-Germain, Barca face Real Sociedad in La Liga at Camp Nou on Saturday.
"First we have to think about the league," said Ter Stegen.
"I know how tough this is for the fans, but now we have to think about getting some rest."