They also expressed dismay over the debate sparked by FIFA president Sepp Blatter's remarks about the 2022 World Cup being staged in winter or summer, without him talking to them first.
The European Club Association (ECA) expressed "major concerns" about the way world football is governed, with the body which represents 197 clubs calling for a greater role in the decision-making process.
"I wouldn't say we are at war, the clubs are very patient, but we have our limits," Sandro Rosell, the president of Spanish champions Barcelona and an ECA vice-president, told a media conference after the assembly.
"We hope UEFA and FIFA will hear what we have to say to them. We have no doubt they will listen to us and consider that what we are asking for is logical and fair."
The ECA stress they work closely with UEFA, European football's governing body, but at the heart of their concerns is their relationship with FIFA.
The world governing body has added eight additional dates for international fixtures to the match calendar from 2011-14, including Wednesday's round of friendlies, and the ECA are profoundly concerned at that change.
JUST NONSENSE
Michele Centenaro, the ECA's general secretary, said:
"The ECA primarily questions the way FIFA reaches decisions heavily affecting club football without the involvement of the clubs themselves and believes that modern football needs democracy, transparency and certainty of rules."
The ECA points to this week's round of friendlies as an example of where they are not being heard.
Umberto Gandini, an AC Milan director and vice-chairman of the ECA, said: "There is not a national team manager or a club manager who is happy there is an international friendly match tomorrow. It's just nonsense.
"The national managers do not have the players for long enough and the club managers are left with three or four players for training before this weekend's league matches and the restart of the Champions League next week.
"We suddenly realised that FIFA can alter the international calendar when they like. This week's friendlies are the result of FIFA's poor logical planning."
The clubs are also angry at the way Blatter has made various unilateral announcements about the 2022 World Cup, which was awarded to Qatar in December, and his views on whether it may be held in the summer or winter months.
WORLD CUP
ECA board member David Gill of Manchester United told reporters the clubs were surprised about how the debate over the 2022 World Cup developed, sparked by Blatter's comments.
Last month Blatter said he expected the World Cup to be in the winter but this week said he now expected it to be in the summer of 2022 although no formal discussion has taken place.
"There has been concern obviously in the way this debate has manifested itself. That is the view of more than 100 clubs and t
