Barkley was filmed arguing with the driver late on Sunday after chips were spilled in the back of his cab.
"He is travelling with the squad," said Lampard. "In terms of permission from Ross [to go out on Sunday], I don't expect to be asked for that.
"To address the issue, he hasn't breached a club code – the lads were given a day off. He hasn't committed a crime, but I think he has been naive to be out before a Champions League game.
"He has admitted that. I like Ross, I have had no problem with him and he has admitted he made a mistake. I will take that at face value and move on."
At 25 years old, Barkley is now one of the more experienced players in Lampard's travelling party for the clash at Stade Pierre Mauroy.
However, Lampard insisted he is not concerned about his youngsters being embroiled in off-field incidents.
"It is my responsibility to tell them about their responsibilities," he said. "I do it constantly, as do the staff in the academy.
"They live in a modern day. I don't understand why, but people pick up their phone and video what happens. We have a very good bunch, good lads.
"I made mistakes as a player. I have confidence in them and they have to take on responsibilities on the pitch."
N'Golo Kante missed Chelsea's 2-0 loss against Brighton and Hove Albion on Saturday due to a hamstring complaint, but he took part in training on Tuesday and will undergo a fitness test ahead of the clash with Lille.
"He got through [Tuesday's session] okay," said Lampard. "It's one that we have to assess. We are positive.
"It doesn't relate to his injury from the Europa League final. The fallout of that meant he has had a broken pre-season.
"He has had a few niggles, some bad luck. Everyone is working to getting him fit."
The Blues suffered a 1-0 defeat to Valencia in the Group H opener.