Brendan Rodgers reminded Leigh Griffiths on Wednesday night he is not on holiday after images emerged of the troubled striker attending a race meeting.
The 28-year-old Scotland striker checked into rehab last month after the Parkhead boss admitted he had 'ongoing issues.'
Pictured at Newcastle Races on Saturday, Griffiths took to social media to slam claims he suffers from either a gambling or drug addiction.
However, with the player having been left behind for professional treatment while team-mates attend a winter training camp in Dubai, Celtic boss Rodgers said: 'Leigh was off on grounds of his health so the club are supporting him with that. I've nothing much more to say on it until I, one, speak to Leigh. And, two, see something. But that will not be until I get back.
'I just need to see where it is all at because he is not on holiday.
'I think it's one where I will take a deep breath and look at it.
'It's very important he understands why he is off and why he has been given the time off and why he has to maximise that time in terms of getting better.
'That's about getting specialist help and lying low and focusing on the simple things in your life that will allow you to be better.
'I haven't spoken to him yet. A designated person at the club is dealing with everything with regards to Leigh and I will pick that up when I get back.'
Rodgers says there is no projected timescale for Griffiths to return to training.
Speaking after Celtic signed Vakoun Issouf Bayo, Timothy Weah and Oliver Burke to bolster their attacking options in his absence, however, he warned the striker that the club can only help him if he wants to help himself.
'Ultimately he is a Celtic player and the club are paying him a lot of money.
'But in these instances you have to support the player.
'Money doesn't count for anything if the player isn't in good health.
'We need to support him, which the club is doing amazingly.
'But there is also a responsibility for Leigh Griffiths.
'Players who have dealt with any types of issues, it's admitting that responsibility and knowing where you are at, really.
'It's the only way you have to move forward, really.
'It is important, if you have these issues - there are ways in which to deal with it.'
Reacting angrily to the newspaper pictures which appeared to show him drinking and gambling in Newcastle, Griffiths put out a statement saying: 'I am off work due to my mental health state. NOT GAMBLING, DRUGS, or any other issue that has been written about me since December.
'The stories, the tweets, the lies that come out people's mouth is laughable, but I suppose if they're talking about me, they are leaving someone else alone.'