Arsenal play away to Rennes in Thursday's first leg, but Lacazette will not be able to feature in either that match or the return game as he serves the remainder of a three-match ban.
The striker was sent off in the first leg of their last-32 clash with BATE for catching Aleksandar Filipovic with his elbow, and UEFA subsequently decided to suspend him for three matches.
But Emery is optimistic Arsenal will be fine without Lacazette.
"Maybe it [the three-match ban] can be a surprise, maybe not," Emery said in his pre-match news conference.
"We know, usually, when you had a red card, you can take minimum one and maximum three [match ban].
"I spoke with him and he said to me, he was asking for one match and I, in the worst case, I said to him in my opinion it was three.
"We have players and also we have confidence with all the players to play without Lacazette."
Rennes have been somewhat boosted by not having a Ligue 1 match at the weekend, meaning they will have had an eight-day break when they host Arsenal.
It was put to Emery that the Premier League could have helped Arsenal, with Mauricio Pochettino recently accusing those in charge of England's top flight of not helping the teams playing in Europe, but the Spaniard seemed reluctant to go on the offensive.
"My opinion is the same," Emery added. "I respect them. The Premier League decided the schedule for our matches.
"We adapted. Our adaptation is preparing the matches with the days we can have. Our habit is to play a lot of matches in the week.
"You ask me if I prefer sometimes more time to prepare matches, maybe yes. This match we don't have an excuse, we have time to prepare well."