The Brazilian forward, 25, was photographed at a Paris nightclub in the early hours of Sunday morning.
Emery, however, insists he is not concerned about Neymar’s lifestyle.
The Spaniard said: “He is very responsible. In training, he is great.When he’s not on the pitch he can enjoy his time with his friends. He then comes back and plays well.
“We have to give the players the flexibility of living their own lifestyle. He is young, and he also needs to go out, but he is still responsible. He will be on the pitch against Celtic.”
PSG are already assured of a Champions League last-16 place but they want to finish top of Group B ahead of Bayern Munich.
The French giants showed their class on matchday one by rattling in five goals at Celtic Park and they will look to maintain that level in tonight’s clash in the Parc des Princes.
Emery said: “We want first position. To win the group we have to beat Celtic. We want to have the best performance possible and we want to play with the best players. Bayern are still in contention.
“So we have to be aggressive, dynamic and get the three points.”
The only player missing from PSG’s galaxy of stars is Italian midfielder Thiago Motta, who recently had knee surgery.
Belgian right-back Thomas Meunier is expected to return to the side after recovering from a knock picked up on international duty.
Emery admitted the Champions League opener at Parkhead in September was the perfect way for his club to put down an early marker.
But he knows Celtic will be trying to salvage some pride in the French capital.
Emery said: “The first game was really good for us. Our team has shown we want to win and go far in this competition. Celtic are a very good team with good players who play for their national teams.
“I’m sure this game will be difficult but we know the importance of getting three points. We have to play at a very high level for the 90 minutes.
“We also need to improve. We have to be good individually and collectively. There is competition for places in the team which is good for us as we have a lot of games coming up before Christmas.
“It is important to keep this collective spirit and I’m very happy with the players who are on the pitch and the ones who are waiting for their opportunity.
“We will try to maintain our recent level of performance in this game. We are changing players and many of them have shown they are ready. We always have the same performance even when we change players.”