Messi cut a disconsolate figure on Tuesday following his side's agonising semi-final exit to Chelsea, who fought back from 2-0 down to draw 2-2 on the night and claim a 3-2 aggregate victory.
Arguably the turning point in the contest came early in the second half when Messi smashed a penalty against the crossbar after Didier Drogba was adjudged to have brought down Cesc Fabregas.
Had Messi converted his spot-kick Barcelona would have been 3-1 up and effectively assured of a place in the final against a Chelsea side reduced to 10 men following the first-half dismissal of John Terry.
Fernando Torres' last-gasp equaliser, which came as Barcelona swarmed forward desperately in search of the goal that would seal the tie, shattered the Catalans' hopes of reaching a third final in four seasons.
Guardiola however issued a vociferous defence of Messi, who has now failed to score in eight games against Chelsea.
"We've gotten to where we are today thanks to this kid," Guardiola said. "More than ever I want to thank him for what he's done for us.
"My admiration for him knows no limits. He's daring, he's brave, he plays fantastic in different conditions.
"We played in Pamplona and it was 10 below zero -- very cold -- and he wanted to play and win the game. He's an example for all of us.
"His competitiveness, how he pushes us all to be better. I've got no doubt that he's going to experience a few difficult hours now because he's a competitive guy but this is what is beautiful about football.
"Sometimes you smile and sometimes it's your turn to be sad."
Guardiola said Barcelona's concession of a goal from Ramires on the stroke of half-time had proved crucial. Prior to that Barcelona had led 2-0 and appeared to be sauntering to a routine victory.
"I think that at 2-0 at half-time we would have believed we would do it, but at 2-1 it was bad for us psychologically," Guardiola said.
"Even so, we went out in the second half, we had a penalty but we didn't score and then they they got stronger and it was difficult for us to score with the minutes we had left.
"It's not easy to score. We were not a team that can play in lots of different ways. We have a peculiar way of playing and this is why the opposition adapts themselves to us.
"Anyway, we will go away and look at it and decide what is best for the institution."
Guardiola admitted however he was struggling to pinpoint weaknesses in his side who once again dominated possession -- by a margin of 72 percent to Chelsea's 28 percent -- but were unable to land the decisive blow.
"You look at the team and try to tell them what they did wrong, why they're not in the final," Guardiola said. "And I don't know what to tell them.
"At the end of the day you're out of the final and that's all that matters. Sincerely I think it wasn't our turn.
"We did everything we could -- absolutely everything -- but we got to a semi-final and lost.
"No matter what we did it wasn't enough. And this is what counts. Probably we did something wrong and we need to see what that was and try to fix it in the future," he said.
"You have to praise Chelsea for their defensive display -- for their courage, for their bravery, for their mental strength in knowing that they had to play this game."