Lionel Messi believes Barcelona played well in their Supercopa de Espana defeat to Atletico Madrid, but has called on Ernesto Valverde's side to cut out "child mistakes".
Barca went down 3-2 to Diego Simeone's side in Thursday's semi-final in Jeddah, Saudi Arabia, as Atleti teed up a final with Real Madrid.
After Koke had opened the scoring for Atleti, Messi equalised with a fine strike before Antoine Griezmann put Barca ahead against his former club.
But with Barca having had two goals disallowed by VAR, Atleti came from behind to claim a dramatic win thanks to Alvaro Morata's penalty and Angel Correa's effort.
Messi insists Barca must not be too down about the level of their display, though conceded they cannot continue making basic errors.
"It is a pity, we played a great game, after a long time we returned to have good feelings, having control and attacking all the time," Messi told reporters.
"We lost due to specific errors when they were almost out, in less than 10 minutes they had a result that we should have closed.
"Today we took a step beyond defeat but we are aware that we have not been doing things as we want, we do not want to make child mistakes again.
"It hurts because it is a title and we wanted to be in the final and win it, we played a good game but unfortunately we did not get the victory.
"We are still working and trying to improve, now we will have more days to prepare the next game, we have much to improve and although we have not been doing good games we will try to recover the game."
The defeat will put more scrutiny on the position of Valverde, but Messi insists the squad must stick together behind their coach.
"It is normal when there are defeats and the objectives are not achieved," Messi added.
"People see that their team does not play as they would like, as we would like, it is normal for them to talk but we have to be closer than ever, it is a difficult situation because we missed a title we wanted but we have to look forward."