The G14, made up of the 18 biggest teams in Europe, are supporting Belgian club Charleroi in their lawsuit against FIFA over the loss of Moroccan midfielder Abdelmajid Oulmers in 2004.
Charleroi are reportedly seeking more than 600,000 euros from FIFA in a case before the European Court of Justice.
If the club win the lawsuit it would mean the end of international competition, but for a few teams, UEFA claimed.
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"It would be the end of the national team game. A World Cup would take place with only Spain, Germany, Italy, France and England and that would be the end," UEFA spokesman William Gaillard told the BBC.
A FIFA defeat "would be the end of national football for any football association outside of the big five in Europe," Gaillard insisted.
"I was talking to Brazilian, Scandinavian and Eastern European football experts, and they all said we would never see our stars playing for the national team again."
"Recently the head of the Irish FA said if we have to pay for our stars we would never see Robbie Keane playing for Ireland again.
"There's no way the Brazilian FA could pay for one fifth of the players."
G14 spokesman James Thellusson said the group was reaching out to UEFA and FIFA to try "to get some form of amicable solution."
"The key goal for G14 is finding a solution to the issues of player release, player insurance and governance, as it has always been," Thellusson said.
"The issues that are at the heart of the Charleroi case are the issues that need to be resolved."
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