"The Champions League punishes you for that".
Valverde, who named the same side as the first leg, didn't make his first substitution until the 81st minute and said the buck stops with him for the defeat.
"We are here and we deserved it and I am really happy about that".
Daniele De Rossi converted the penalty for a 2-0 lead, trimming the aggregate margin to 4-3.
Barcelona president Josep Bartomeu has apologised to fans after being knocked out of the Champions League on Tuesday night.
'It was a very big disappointment for the season we have had so far'.
Meanwhile, reports have it that the veteran midfielder is considering a move to China, and he hinted this mighy be his last Champions League match.
Messi was a crucial component in almost all of those triumphs for Barcelona, but the playmaker performed below expectations in the team's recent Champions League failures.
"In 2018, Barcelona has played 24 games".
"I thought that when the game was equal, with them needing one more goal, there was enough experience in the team to see the game out", he said.
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Dembele was on the bench Tuesday, entering the match in the final minutes as a substitute.
Iniesta has won the Champions League on three occasions and will go down as one of the greatest players to play in the competition. "The truth is that they were very good and we weren't".
Striker Patrik Schick almost added a second, but he nodded a header just wide after being left unmarked in the box, and then came close again with a stabbed effort which was heroically thwarted by Gerard Piqué.
While Barca's Treble dream died in Rome, they can still win a Double this season - they're 11 points clear at the top of La Liga and through to the Copa del Rey final.
"We had high hopes this season and it has escaped us again", added the 33-year-old, who also acknowledged that the game could have been his last in the competition for Barca amid uncertainty about his future beyond this season. "But we don't have any other option".
"I feel bad because we wanted to reach the semifinal, but we didn't deserve it today".