The Gunners came back from a 3-1 away loss against Rennes to progress to the last eight with a 3-0 home success.
While they made easy work of the French side, Kolasinac would prefer a more straightforward progression in the next round.
Kolasinac said to reporters after the game: "It's always very difficult when you lose the first game. It is something we are going to work on in the next round. The key will be to start better than we have.
"We didn't put ourselves in a good position at the end of that first leg. Having said that, I think that away goal was crucial for us. It was difficult because we had to play with 10 men for about 50 minutes of that first game as well [after Sokratis Papastathopoulos was sent off].
"We made it difficult but we knew how strong we are at home and we deservedly went through."