A shock 1-0 defeat at BATE Borisov last week - a team who had not played a competitive game in two months - means Arsenal must turn the last-32 tie around to progress in the tournament.
Koscielny insists Arsenal view the competition with respect, describing the Europa League as "top tier", but qualification back to the Europe's premier competition is key.
Asked whether the team are missing out by not being in the Champions League, Koscielny told reporters: "No, no. The Europa League is still a big competition.
"It is still a European cup, but of course when you are in the Champions League you want to be in there every year and next season we want to be in the Champions League.
"But the Europa League this season still has a lot of big teams, it is a top-level tournament, there is Chelsea, Napoli, Valencia so it I think it is a big competition, more than last year, and every year it is more intense.
"Last year Atletico Madrid won the cup, so for us it is big opportunity to go in the Champions League.
"Now we have a game in front of us like tomorrow to get to the next rounds and try to get to the final and be in the Champions League next season."