Como lost on penalties after the score ended 1-1. Patrick Cutrone struck for Como, with Samp's goal coming from Nicholas Ioaunnou.
The tie also saw Como defender Raphael Varane forced off with a knee injury.
Cesc said: "The first half was good, in the second we dominated trying to create superiority, I liked it, we have to improve. In the second half we were superior, Belotti was a necessary substitution. An opportunity like that of Strefezza must be a goal.
"We will analyze the match well and we will improve from here. We are at the beginning and it is a new level for us, they must feel what it feels like to go and play with Juventus and feel pressure. Football is like that and we have to raise the level."
On Varane's injury, he said: "He has to play, he has to start getting playing time. He got hurt, I'm sorry for him, it looks like his knee but I can't tell you anything."
On Sampdoria, Cesc concluded: "They have a better chance of going to Serie A, they have created a team with Coda and Tutino. A team that wants to win."