Barca won 3-2 on Saturday night thanks to an own goal in injury-time.
Afterwards, Calero insists Levante deserved something for their performance, stating: “The result is unfair. We deserved, overall, to get something. But this isn't what you deserve if it's not what you get. This is elite football.
“On a footballing level, the team did what they had to do against Barça. They wore you down a lot.
"Our objective was to try to get those two passes right, which we did on several occasions, and we were damaging. But this team doesn't let you."
Calero also said, "It was a very specific game plan for today. We had the chance to hurt them on several occasions, trying to break the offside trap, but that was the idea behind this game plan. We hurt them but we couldn't do it for the entire game.
“We have to stick to our guns. Teamwork, effort, solidarity, and certain hallmarks. But obviously, they're 0 out of 6. You don't live off feelings, you live off points. Getting points gives you confidence, but I don't want to lose confidence by not getting points.”