Brendan Rodgers expressed his disappointment after a fan came out from the stands to confront Paris St Germain's Kylian Mbappe during the French side's 5-0 Champions League win at Parkhead on Tuesday night.
Celtic look set to face another UEFA punishment after the supporter raced onto the pitch moments after PSG had taken a 3-0 lead and aimed a fresh-air kick at the 18-year-old French forward.
UEFA have already fined Celtic 11 times in less than six years over fan behaviour issues ranging from pro-IRA chants to fireworks, crowd disturbances and illicit banners.
Other Hoops fans were unhappy with the disruption just before the interval and Rodgers said the Parkhead club will take its own action.
He said: "The crowd reaction said it all. It is disappointing at any ground that a supporter gets on to the pitch.
"I am sure the club will deal with that. It shouldn't be anything that we should see on a football field. The crowd in their reaction told you everything you need to know.''
Rodgers admitted his side were simply outclassed by the free-spending French club whose multi-million pound frontline did the damage in the first half of their Champions League Group B opener.
Brazilian star Neymar opened the scoring in the 19th minute, Mbappe added a second in the 34th minute before Edinson Cavani netted with a penalty five minutes before the break.
Parkhead defender Mikael Lustig put through his own goal before Cavani grabbed his second with a clever header to hand the home side their record home defeat in Europe.
The former Swansea City and Liverpool boss said: ''This is a level where you have to look after the ball and you have to make it work for you.
''In the first half we didn't do that, we were playing like under-12s at times.
''So like I say, it is confidence, belief. We are missing some decisive players as well who can help us at this level but it is always going to be very tough.
"That is the reality of it.
''I don't want to be too harsh on the players. They (PSG) are the potential champions of this tournament and where we are at, with all due respect, and where those guys are at, it is not just one or two levels, it is three or four levels away beyond.
''We always have to be competitive and we weren't for that first period but the second half was much better and the supporters acknowledged that.''