The proposed European Super League is the result of "selfishness and greed," says Uefa vice-president Fernando Gomes.
It was revealed last week that talks had taken place over the creation of a new £4.6bn competition.
Outgoing Barcelona president Josep Maria Bartomeu said the club had begun proceedings to join the league.
"It violates all principles of sporting merit. It would be a self-proclaimed privileged club," Gomes said.
The European Super League would involve the top sides from across the continent, although discussions are at an early stage.
In his resignation speech, Bartomeu said Barca had started proceedings to help their financial future.
However, Gomes said it would have "no passage of support" in his native Portugal.
"It deserves my refusal because the world is currently experiencing its greatest challenge, at least for the last century, and the last thing it needs is the exacerbation of selfishness and greed," he added.
"In my opinion all governing bodies should refuse it in a very clear way."
Former Arsenal manager Arsene Wenger said that the proposed league would be a serious blow to the Premier League.
"The other leagues try to destroy the advantage the Premier League has. For them the best thing to tame it is to create a European league," Wenger told the Guardian.
"If they get the agreement from the English big clubs it will happen."
Fifa said on Wednesday it was not aware of any agreement for Barca to join the European Super League.
"As we already said last week, the topic of a so-called 'European Super League"' comes up every now and then and Fifa has no wish to comment further on this since there are already well-established football institutional structures to deal with it," Fifa said.