Athletic Bilbao, Atletico Madrid, Real Betis, Celta Vigo, Espanyol, Getafe, Granada, Real Mallorca, Osasuna, Rayo Vallecano, Real Sociedad, Sevilla and Real Zaragoza issued a list of demands which included a call for the professional league (LFP) to adopt a "transparent and regulated" system for fixing match kick-off times.
They urged LFP president Jose Luis Astiazaran, who has been accused of helping some clubs with favourable kick-off times that disadvantage others, to convene a meeting of all 20 La Liga clubs next Tuesday, August 14, to discuss and vote on the demands.
The rights dispute escalated last month when Canal+, which is owned by the Prisa group, said Mediapro's announcement of an auction for La Liga TV rights was "illegal" as it included clubs who it says have signed exclusive deals with Canal+.
The broadcaster cites a Spanish court ruling that limited rights contracts to three years and which it said nullified some of Mediapro's deals. With less than two weeks to go before the season is due to begin a solution appears remote.
In their joint statement on Tuesday, the 13 clubs complained the dispute had created "a situation of serious legal insecurity which affects all the clubs".
They called on broadcasters to settle any outstanding debts with the clubs and to drop any legal demands against them.
"In the event that an acceptable solution for a majority of first division clubs is not achieved, the clubs are prepared to adopt whatever measures necessary, including postponing the start of the 2012/13 league championship," the statement said.
Many of the 13 are also unhappy with the way Real Madrid and Barcelona dominate revenue from audiovisual rights due to the lack of a system of collective bargaining and income sharing like those used in rival European leagues.
Atletico chief executive Miguel Angel Gil warned last week that the future of La Liga was under threat unless Real and Barca agreed to change.
