Fifa president Gianni Infantino “strongly disapproves” of the breakaway European Super League and says the 12 clubs will have to “live with the consequences” of their decision to join.
Premier League clubs Arsenal, Chelsea, Liverpool, Manchester City, Manchester United and Tottenham are part of the proposed league.
“There is a lot to throw away for maybe a short-term financial gain for some,” said Infantino.
“Either you are in or you are out.”
Meanwhile, UK Prime Minister Boris Johnson met with the Football Association, Premier League officials and fans’ representatives on Tuesday, after which the government said it will take “whatever action necessary”, including legislative options, to ensure the proposals were stopped.
Johnson’s stance is supported by Labour and the Liberal Democrats.
A statement released after a meeting between the Premier League and the 14 clubs not involved said they “unanimously and vigorously” rejected plans for the competition.
It added that it is considering “all actions available” to stop the competition and asked the six teams to end their involvement immediately.
The Football Supporters’ Association has met with the government and the Labour Party to discuss the impact of the breakaway league.
Uefa president Aleksander Ceferin called on the English clubs to “come to your senses”
Real Madrid president Florentino Perez said the new league was needed to “save football”