Brendan Rodgers says Moussa Dembele conceded in a private meeting that nobody from Celtic made promises about him leaving the club.
The striker joined Lyon in a £19.7m deal last Friday after hitting out at Rodgers on social media, insinuating he had not kept his word after Celtic had rejected an initial proposal from the French club.
In a final statement on his spat with the player, following their 1-0 Old Firm win over Rangers on Sunday, Rodgers detailed the sit-down he had with his staff and Dembele, who he believes crossed a line with his behaviour.
"The whole episode was disappointing - and I'll say a bit on it and then that will be it then, because it's been a bit one-way," Rodgers said at Celtic Park.
"I had a really close relationship with Moussa. I enticed him to come here, with a plan going forward. He was desperate for the move, of course, but we wanted to try and keep him because we didn't have another option.
"But then there was a line that was overstepped, from a behaviour perspective, and I've been in these situations enough times to know if you can pull it back or not. And, like I said, I needed to speak to Moussa - and I had a number of my senior staff with me.
"I just asked him; can you tell me and the guys in the room that you received promises from me, or any member of Celtic? And quite clearly and categorically he said 'no'. So, once he said that, that was fine then, I said 'you can now go, if you can get the move'.
"There is a lot of integrity here within our staff and with our team and how we work. I understand the model here at Celtic, with these talents coming in. You develop them and then you move them on. But there was a lot of stuff that was said that was not so nice and, ironically, not true.
"But Moussa is happy - he's got his move. Deep down I know he's a good boy, he's done great for us here and I wish him all the very best at Lyon."
Rodgers appeared relieved to have the episode behind him, after summer-long reports of conflict with the board over transfers - but he remains one striker down in his squad as he looks to clinch a third successive Scottish Premiership.
"I have to deal with it," he said. "I'm a striker down, but I'll always protect the mentality of the group and we've got young players to come through.
"The bigger picture - I always think of that. I think of Celtic, the squad, the spirit within the team. I've got young Ryan Christie - there're opportunities for him now. I'll look forward to that coaching element now until the end of December, as opposed to talking about transfers."