EU chief Juncker: We'll make an example of Britain that no-one will want to follow
Asked by Bild am Sonntag newspaper if other member states would follow Britain's example in quitting, Juncker said: "No. Britain's example will make everyone realise that it's not worth leaving."
He added: "On the contrary, the remaining member states will fall in love with each other again and renew their vows with the European Union."
The EU's 27 leaders plan to declare "Europe is our common future" during a meeting in Rome next week to mark 60 years of the bloc.
Juncker said Britain would need to get used to being treated as a non-member.
"Half memberships and cherry-picking aren't possible. In Europe you eat what's on the table or you don't sit at the table," he added.
British Prime Minister Theresa May has made it clear that she plans to take Britain out of the European single market as part of Brexit, potentially damaging London's role as a financial centre.
HSBC, JPMorgan, and UBS have all warned about job relocations. Jamie Dimon, CEO of JPMorgan Chase, told Bloomberg at Davos that the bank will likely move more people than previously thought. "It looks like there will be more job movement than we hoped for," Dimon said. The bank employs 16,000 people in the UK.
Juncker said more countries would join the EU in future, although not during his time in office, which runs until 2019, because none of the candidates fulfils the conditions yet.
(Reporting by Michelle Martin; Editing by Ruth Pitchford)