The Celtic boss said: "I thought the team were magnificent. It is bitter-sweet really, it is hard to take losing the game in the manner in which we did, but I am so proud of the players, I think they gave the club and the country a huge shot in the arm.
"There is a mixture of disappointment and anger that we didn't see it through to the end of the game.
"The players are hurting, they are angry, whatever you want to call it, but it gave them a real taste of playing in the Champions League at the highest level and they played fantastically well.
"No one gave us any hope, but I think we have won a lot of admirers.
"They were brave, I couldn't ask any more from them, maybe just 30 seconds more to see it through.
"It would have been fantastic to pick up something from this gam,e but we didn't budget for anything from it. I hope they take plenty from the game.
"But there are no recriminations and no criticism. I think we leave with our reputation intact."
Celtic remain second in the group with four points from three games ahead of the return game against Barcelona in a fortnight's time.
Barca coach Tito Vilanova said: "We knew Celtic were dangerous, they were fast and powerful in the air.
"I this we deserved to win the game, their keeper played well and credit to them, but I think we controlled them pretty well.
"I believe that Celtic have a chance to qualify, they have two more matches at home so it is possible."