Fifa boss 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.
“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.
Downing Street added: “No action is off the table.”
The proposed tournament would see teams play one another in midweek games in an attempt to have more matches between the big-name clubs.
The other clubs involved are AC Milan, Atletico Madrid, Barcelona, Inter Milan, Juventus and Real Madrid.
The plans have been heavily criticised by fans, pundits, football’s governing bodies and members of the UK government.
“It is our task to protect the European sport model. If some elect to go their own way, they must live with the consequences of their choices,” said Infantino, the president of world football’s governing body.
“They are responsible for their choice completely. This means you are either in or you are out. You cannot be half in and half out.”
‘Gentlemen, you made a huge mistake’
There have been protests outside the grounds of the Premier League clubs who have signed up to the league.
Leeds players also wore T-shirts saying ‘Earn it’ next to the Champions League logo and ‘Football is for the fans’ before their 1-1 draw with Liverpool on Monday.
On Tuesday, Uefa president Ceferin called on the English clubs to “come to your senses”.
Directly addressing the owners of the six Premier League clubs, he said: “Gentlemen, you made a huge mistake. There is time to change your mind.
“Come to your senses. Not out of love for football – I don’t imagine you have much of that – but out of respect for the people who bleed for the team, out of respect for the home of football. I know we are right and they are wrong. It is a match we cannot lose.”