LaLiga president Javier Tebas has threatened to force teams into training camps if players continue to flout medical protocols.
Spain's top flight was due to resume on Thursday with the Seville derby between Sevilla and Real Betis at the Ramon Sanchez Pizjuan, three months after playing was suspended due to the coronavirus pandemic.
Lockdown measures across the country have been eased in recent weeks, with life beginning to return to relative normality, but some protocols remain in place and a few players have broken them.
Four Sevilla players were photographed at a barbecue in a group of 12 people at a time when any gathering was supposed to be limited to 10, while Barcelona confirmed on Thursday that Nelson Semedo was missing from training "as per protocol established by LaLiga".
The Portugal defender was reported to have attended a party and broken social-distancing guidelines earlier in the week.
Tebas has now warned players that LaLiga will impose rules forcing them to work in training camps if they continue to ignore the regulations.
Speaking to reporters on a conference call, Tebas said: "What we are thinking is that if players keep doing this we'll have to consider having obligatory training camps.
"We wanted to do that but over the last few weeks we saw the clubs were obeying the protocols, but if we start to see three or four players at each club disobeying these rules then we'll have no other remedy than to impose training camps.
"We hope we don't have to but if people keep going to barbecues and parties we might have to. LaLiga has shown a lot of faith in players by not enforcing camps so, [we ask them] please, return that confidence, and don't break the rules as that harms LaLiga and people's health in general."