Neil Lennon says Celtic are "not satisfied" with Olivier Ntcham's reported comments about the club and will speak to him about his "mindset".
The 23-year-old French midfielder was quoted as saying he was disappointed not to join Porto last season and flattered to be linked with Marseille.
He also felt that Scottish football was not challenging enough.
"You can imagine, we find the comments untimely and not particularly accurate," manager Lennon said.
"I think it is fair to say that a lot of us, would it be management, players or people at the club, were not satisfied with the comments."
Ntcham, who joined Celtic from Manchester City in 2017, made 37 appearances as the Glasgow side won the domestic treble last season.
He was not with the squad as they headed for Bosnia-Herzegovina to face Sarajevo in Tuesday's Champions League first qualifying round first leg, as he was with the France squad that reached the semi-finals of the European Under-21 Championship.
"That will be addressed when Olivier comes back," Lennon said while stressing that Ntcham has a future at Celtic as he remains under contract until summer 2022.
"When I speak to Olivier, it will be done privately, but I will be speaking to him about his mindset and his attitude towards the club as well, which, the way it came across, didn't look good."
Meanwhile, Lennon stressed it was "as you were" with regards to Scotland left-back Kieran Tierney, who has been linked with Italian Serie A club Napoli with Arsenal having had a £15m bid rejected.
Tierney was with the squad on pre-season in Austria but is working his way back to fitness after a double-hernia operation in May.
"I have taken no notice of the headlines," Lennon said. "I am well aware of where we are in terms of the situation.
"I spoke to Kieran in Austria and, to be honest, I haven't really seen much of him because he came back early for rehab, so has not been on the training ground as yet.
"It can be an unsettling period for any player and that is understandable, but until a club comes up with any sort of realistic valuation of the player, we don't have to do anything and we won't."
Celtic 'driven' by AEK exit
Celtic's qualifying exit to AEK Athens last season is driving them to reach the Champions League group stage this time round, says skipper Scott Brown.
The Scottish champions were knocked out in the third qualifying round by the limited Greek side after a 1-1 home draw and 2-1 defeat in Athens.
"What happened in Athens last year was hard to take for everyone," said Brown, 34, ahead of the opening qualifier against Sarajevo.
"We thought we were the better team over two legs but just couldn't get the ball in the back of the net.
"It is always on the back of your mind. That's the things that drive us on to try to get into the Champions League. It's huge for me."