The Bhoys took an early lead through Giorgios Samaras but Andres Iniesta levelled on the stroke of half-time before Jordi Alba broke their hearts with an injury-time winner at the Nou Camp.
It was a stellar performance by Celtic who almost hung on for a famous draw and Lennon was full of praise for his players who were devastated to lose in such a heartbreaking manner.
“The team were just magnificent and the emotions are bittersweet,” said Lennon.
“Just 30 seconds more, that’s all we needed to see it through. When the goal went in, I was disappointed and I was angry – not at individuals or the team, just that we couldn’t see it through.
“So it’s hard to take losing in the manner we did, but I’m so proud of the players. They’ve given the club and the country a shot in the arm.
“They’re hurting, but it won’t take much to pick them up. They’ll take so much satisfaction from what they did here. This was a taste of Champions League football against the greatest players in the world. They accepted that they wouldn’t have the ball for long periods, but they didn’t panic.
“We were compact in midfield, the full-backs did their job and we looked a threat going forward.
“It doesn’t surprise me they stepped up. I told them before the game ‘No one outside the dressing room believes we can get anything’. But I believed in them and so did they.”