The Reds claimed the emphatic victory over the Spanish champions courtesy of Saido Mane's first goal for the club, a Javier Mascherano own goal, and second half strikes from Divock Origi and Marko Grujic.
A key component of Liverpool's win was their high defensive line and intensity of closing Barca's players down to limit their space to influence the game and Klopp feels there were several positive lessons for his players to learn from the result.
"It was a wonderful lesson for us today because we did really well, but when we become a little bit passive, it is a problem for us," he told Sky Sports. "That is normal, not only against Barca, but especially against Barca.
"Wonderful goals, great challenges. We wanted to do high pressure, which I think is important against Barca. But of course you cannot do it the whole time and you have to be compact against Barca.
"We have to learn better that when we stay deep, we must be active and it was a little bit of a problem, but there were also some wonderful moments.
"I am really happy and emotional about the reaction here in London. Liverpool came to London today and it was really nice to have all these people here, 90 per cent on our side, which you do not often get in a match."