Europe's top leagues want colleagues on a UEFA panel to unite against FIFA's multi-billion pound plan for new competitions.
Lars-Christer Olsson, the CEO of the European Leagues, said after a board meeting of his 32-member group on Thursday that FIFA had been acting with "a clear lack of consultation and transparency."
Since March, FIFA president Gianni Infantino has pushed for approval from his ruling committee for a quadrennial 24-team Club World Cup and a biennial Nations League for all national teams.
A 12-year deal with a Japanese-led, Saudi Arabian-backed consortium for the competitions would start in 2021.
Olsson's comments come after he last month criticised FIFA for an "expansion drive" following the suggestion of a 48-team 2022 World Cup.
FIFA's ideas require taking weekend dates from European leagues for its own competitions.
Olsson said FIFA's proposed Club World Cup prize money would "increase the financial and sporting gap" between clubs playing in member leagues. Each edition would be worth around £2.2 billion, FIFA has said.
On May 16, UEFA's strategy council -- including leaders of European national federations, clubs, leagues and players' union FIFPro -- will meet in France during the FIFA consultation period.
The leagues called on other European officials to "firmly oppose and together stop this unilateral initiative from FIFA."
The £18.5bn investment offer to FIFA includes guaranteed money from the consortium, which wanted agreement inside a 60-day deadline which expires in mid-May.
FIFA has declined to fully identify the investors, citing a non-disclosure agreement.
"This process reminds me of the way the old FIFA acted, which I thought we had left behind," Olsson said.
Europe is the main potential holdout among football's six continental governing bodies.
UEFA sees threats to the worldwide appeal and commercial value of its Champions League, while the Nations League proposal -- including an elite eight-team final tournament -- was created by UEFA last year.