The Spanish league plans to fine clubs that allow empty seats to be shown on television next season.
New regulations require top-tier clubs to fill sections of the stadium which are shown by certain camera angles.
The move is part of efforts to improve the league's product for TV audiences and increase its competitiveness with England's Premier League.
In May 2015, Spain approved new laws so rights to show La Liga matches will be pooled and sold collectively.
Previously, Real Madrid and Barcelona had negotiated their own lucrative deals.