Barca crashed out of the Champions League after surrendering a 4-1 first-leg lead to Roma, who won 3-0 on Tuesday to progress on away goals.
"Messi is like his team-mates," Valverde said. "We are a bit sad and low but we have to face this challenge and want the ball moving again. That's how it is.
"Messi is one of the players who has won more Champions League's during his career. Winning the UCL is really difficult, only one team can win it, so it's very difficult.
"You cannot have a bad moment in this competition and that happened to us the other day."
Barca are unbeaten and top of the table in La Liga, nine points clear of second-placed Atletico Madrid after 31 rounds.
(goal.com)