Celtic face disciplinary action after fans were accused of letting off fireworks during the Champions League visit of Cliftonville on Wednesday, less than 18 months after being fined over a similar offence during a Europa League tie against Udinese in Italy.
The club responded with a strong statement warning that numerous safety issues might prompt them to close section 111 of Celtic Park, which houses the Green Brigade fans group.
And Lennon today appealed to the supporters to provide backing within the stadium guidelines.
"It's disappointing and it's not for the first time," Lennon said of the UEFA charge.
"Our motivation on this is health and safety - the safety of supporters.
"People look as though they enjoy themselves and they do add a lot to the stadium, I have been very vociferous in my support of that section in particular. But there are things they cannot do.
"We are not being over-critical but there are lines to be drawn and they can't cross them any more."
Lennon added: "I'm not a big fan of fireworks. I'm not a big fan of flares being let off in a crowded area. It doesn't do the players any good, it stops the game.
"It's just not necessary. You can still go to the game and enjoy it without having to light the place up as it were.
"They can light the place up in many ways, and they normally do that through colour and singing their songs."