The Gunners were cruising toward a dominant victory when Mesut Ozil put them 4-0 up in the 74th minute after two goals from Pierre-Emerick Aubameyang and one from Danny Welbeck already had them comfortably in front at the Emirates on Thursday.
"They knew that we couldn't open ourselves up, because Arsenal's attack is so quick".
"We're not just playing to participate".
Asked specifically about Arsenal's desire to win the tournament, he added: 'Especially for me because I didn't play previous year in the Europa League with the guys.
The Spaniard also gave fellow summer signings Stephan Lichtsteiner and Lucas Torreira their first starts but, despite marking his first European game in charge of Arsenal with a win, he was left with some frustration.
But the visiting side from Ukraine pulled two late goals back to leave Emery's team without a single clean sheet this season.
"With the four goals, I think we are in a good moment".
"Our disappointment today is the two goals conceded", Emery said. We are speaking before each match to take a mentality of don't concede easy chances.
"But we need to improve and fight to not concede goals like we did in the last few minutes". "We need to continue to improve in this because the last minute at Newcastle and today, in the last 20 minutes, there were two goals, and our success and our challenge is to be competitive for 90 minutes each match and it is one thing to improve".
'I think today is a good opportunity for not accepting goals, but the last 30 minutes, we needed to be better on this competitive aspect'.