Parkhead skipper Scott Brown claimed the Polish side "got a bit over-confident and celebrated in our boys' faces" at the end of a remarkable night at the Pepsi Arena which put a huge and perhaps irreparable dent in the Hoops' group-stage aspirations.
Brown, sidelined at the moment with a hamstring injury, insists the Celtic players will remember Legia's post-match behaviour going into the second leg of the third-round qualifier at Murrayfield tonight.
However, speaking at the Edinburgh stadium before his side went out to train, Berg, who played for Celtic's traditional rivals Rangers a decade ago, denied his players had in any way taunted the Scottish champions.
"Our players were just so happy to play a good game and score two late goals against Celtic, that's what they were celebrating and were so happy about, not because we thought this tie was over," he said.
"For us, it was a big win against a big team. The players were just happy to play the football they did, that's why they were so happy.
"We know the game will be tough, it will be hard, we have to play well and do our job 100% and we expect Celtic to be better.
"So nothing is decided yet."
Legia's Spanish defender Inaki Astiz was also perplexed by Brown's comments.
"I am surprised at those allegations. I saw nothing wrong on the pitch," he said.
"It was just pure happiness from our team from scoring those goals and there was certainly no provocations from our players towards anyone else.
"We were just so happy with the result."
Certainly, Berg said little which could have given Celtic any more reason to be fired up.
The former Manchester United, Blackburn and Norway defender straight-batted several questions about the convincing lead his side were taking in to the match, insisting he was simply content with the advantage his side brought to the home of Scottish rugby, used as Celtic Park is out of commission due to its use at the Commonwealth Games.
"We are happy with the result from the first game," he said.
"If you had said before the game that you could take 4-1 to Scotland we would have taken it, even though we could have scored more.
"It was a good game for us. But we expect Celtic to be better and it will be a tough game.
"We would be disappointed if we don't go through but we would be disappointed if it was 0-0 and we didn't go through.
"The main this is to play well again against another good European team."