The Blues never got going in the opening period and within half-an-hour, had lost their two goal cushion from the first leg.
From that point on, it was a long way back for Pep’s men and they eventually lost the second leg 3-1, losing on away goals with the tie level at 6-6 overall.
“We played exceptional in the second half, but the first one we forgot to be there,” said the Blues’ boss.
“We are a team that wanted to defend aggressively without the ball. In the second half, it was much better but it wasn’t enough.
“Normally we play until half-time at a good level but tonight, we didn’t do that. It’s happened, the opponent was there and we will learn from this.
“We have a team with not much experience in this kind of competition. We will try to be there it doesn’t matter if we play home or away.
ACTION STATIONS: The City team line up prior to kick-off
“At that level, when you concede and play the way we did in the first 45 minutes, it is so difficult. In the second half, we had the chances to score a lot of goals and we didn’t. That’s why we are out.
“In the first half, they could have scored more. Barcelona scored three goals through set-pieces, two penalties and a free-kick, so set-pieces are important at this level.
“That is my only sad thing is the way we played in that first 45 minutes. You can play and the opponent can beat you, but we were not there. In the right moment, we should be there but we weren’t.
“I think we will improve next year. We are going to try, of course we are. This competition is so demanding for the big teams, home and away games. In the special moments, we were unlucky. That’s why we will be looking to the Premier League and the FA Cup and then next season.”