A "furious" Nicola Sturgeon warned Scottish football that its permission to play would be risked if there was a repeat of the situation that saw two Aberdeen players catch Covid-19 following a trip to the pub.
Saturday's Scottish Premiership match between Aberdeen and St Johnstone has been postponed following Scottish Government intervention after eight Dons players were told to self-isolate on Thursday.
All eight visited a bar on Saturday in the city, which has been the subject of stricter local lockdown rules since Wednesday, and the decision was taken to postpone the Perth encounter following talks between sports minister Joe Fitzpatrick and the Scottish football authorities on Friday morning after cases in Aberdeen rose to 101.
The First Minister told a press conference: "It is now clear that all eight of these players visited a bar in Aberdeen on Saturday night. In doing so they blatantly broke the rules that had been agreed between the SFA, the SPFL, and the Scottish Government, which, to put it mildly, is completely unacceptable.
"We are asking members of the public to behave in a highly precautionary manner and when a football club ends up with players infected with Covid – and let's remember this is not through bad luck but through clear breaches of the rules – we cannot take even a small risk that they then spread the infection to other parts of the country.
"The Scottish Government will also be contacting all club captains and managers to emphasise the importance of complying with the guidance.
"I am trying to be diplomatic but I am pretty furious about this situation because it shouldn't have happened.
"But on the upside let's just take the opportunity to underline the importance of this. The decision to allow elite sport to get up and running again wasn't taken lightly. There were a lot of reasons to be quite nervous about it.
"But we gave it the go-ahead because a lot of work went into agreeing the guidance that underpins it. If that guidance is not going to be adhered to, then all bets are off. So let's hope this is a salutary lesson to everyone."
When asked whether the rules for footballers were clear, Sturgeon said: "When we're talking about what happened in Aberdeen, which is football players going to a bar, I don't think there should be any dubiety about that.
"Footballers not only risk compromising the sporting bubbles but high-profile footballers in a city-centre bar also pose a risk of attracting crowds and other people. In any way you want to look at this, and I'm sorry to be blunt, that was not responsible behaviour."
The comments came hours after Aberdeen chairman Dave Cormack had appealed for fans to reserve judgement over the eight players.
However, he later promised to deal with the situation seriously and apologised to the rest of the top flight.
In a statement on his club's website, Cormack said: "With the pressure over this season's fixtures, and the fact that we caused this problem, we were fully prepared to play the game. We are very grateful that the decision has been to postpone, rather than forfeit the game.
"I took the opportunity yesterday to apologise to both football and health authorities, and with our fellow Premiership clubs today."
He added: "Regrettably, what has happened in the last few days has undermined all the hard work that has gone into keeping our players and staff safe. We are now dealing with this internally with the seriousness it deserves.
"In the meantime, I'd like to reassure the relevant bodies, our fans and everyone associated with the club that our already rigorous measures are being forensically scrutinised and that no stone will be left unturned in ensuring that no-one is under any doubt about what must be adhered to."
St Johnstone added: "The club is disappointed at the news of this postponement but the health and wellbeing of everybody is of paramount importance in this situation."
