Ahead of its Congress in Kigali, Rwanda, FIFA on Tuesday announced that the 2026 World Cup will have 104 matches instead of the traditional 64 games due to the expanded format with 48 teams taking part.
The governing body also approved a 32-team Club World Cup which will be played every four years from June 2025.
"FIFA continues its malpractice of making unilateral decisions on the world football calendar, showing complete disregard for the importance of national championships, and the football community in general," LaLiga said in a statement on Tuesday.
"FIFA completely neglects the economic damage these decisions inflict on leagues around the world. Leagues were not consulted about any of the changes presented today, especially about the new annual club competition...
"These decisions do not take into account the competitive, sporting and economic impact on national leagues, clubs and players, by further cramming an already overloaded schedule. FIFA only takes into account a small group of clubs and players..."
LaLiga added that it and other leagues in the World Leagues Forum (WLF), an organisation representing professional association football leagues, would "analyze FIFA's decisions and decide on the most appropriate next steps".
In December, the WLF criticised the announcement of a 32-team Club World Cup, saying it could have damaging consequences for the football economy and player welfare.
The revamped match calendars were approved by the FIFA Council, the main decision-making body of the world soccer organisation.
The FIFA Council has 37 members including president Gianni Infantino, 28 of which are elected by member associations. UEFA, which is Europe's governing body, is also represented on the Council.
Reuters has approached FIFA for additional comment.