LaLiga president Javier Tebas was left "concerned" after Sevilla players were found to have broken lockdown rules by having a social gathering on Saturday.
Ever Banega, Lucas Ocampos, Franco Vazquez and Luuk de Jong were seen congregating in a group of around 12 people in a since-deleted Instagram post uploaded by Banega's partner.
There is a maximum of 10 people permitted at gatherings in Seville, which remains in the early stages of Spain's easing of lockdown measures – though it is set to become the largest city to enter phase two on Monday.
"I appeal to all footballers; you cannot have this attitude. You have to be very careful because we jeopardise many jobs," Tebas said.
"At that gathering there could have been an asymptomatic [person with COVID-19], and it seemed that everyone smoked from a shisha pipe.
"You have to be responsible for everything you do. Security is total on the pitches where they train and in games, but I am concerned about these places and these meetings. We have to be very cautious."
LaLiga chiefs have implemented strict protocols to ensure players remain coronavirus free, meanwhile, in the hope of the league resuming in early June.
The actions of the Sevilla quartet may have put next month's restart in jeopardy, however, and they have each moved to express their regret following Saturday's gathering.
"I want to apologise for what happened yesterday," Banega said on Instagram. "It was a family get together with team-mates but unknowingly, we were wrong.
"For this, I want to apologise to our club, our fans and the society in general. It won't happen again.
"We only want to return to play as soon as possible."
Ocampos posted an apology of his own on social media, saying: "I want to say sorry and acknowledge that we have made a mistake, damaging the image of the club.
"For this reason, we can only apologise to the club, the team-mates and the coaching staff and to society in general.
"We guarantee that we have learned and that actions like this will not be repeated."
Fellow Argentinian Vazquez added: "Regarding what happened yesterday, I admit that it was a mistake. And as such the first thing is to apologise.
"We have failed everyone: team-mates, coaches, the club and LaLiga, but we have learned. It will not be repeated. Let football come back."
In the simultaneously posted messages, Dutch striker De Jong echoed his team-mate's sentiments.
"I want to apologise to everyone who may have been offended by what happened yesterday," he said.
"It will not happen again. We want the competition to return, we just want to play again."
Tebas acknowledged the apologies and said that players must be careful with what example they are setting.
"I am going to emphasise that the players have repented, which is positive," Tebas said during his interview. "The players are an example for society and they must be careful with what they do."
Nearly 29,000 people have been confirmed to have died from coronavirus in Spain, making it the fourth worst-hit country in the world.