But running through the three options for Northern Ireland, Juncker - who was flanked by the EU's Chief Negotiator Michel Barnier and his former Chief of Cabinet Martin Selmayr - said it was up to the U.K.to come up with a workable solution that would avoid the need for a hard border.
The EU is determined to prevent Britain from picking particular benefits of close integration without sharing the costs and obligations, fearing such an example would tear the bloc apart with more countries trying to follow suit.
One shouted at him: 'It's a British issue'.
THE PRESIDENT OF the European Commission has said that there should be no hard border between Ireland and Northern Ireland that the Good Friday Agreement should be "preserved in all its dimensions" following Brexit.
Mr Farage also used his time in parliament to complain that the United Kingdom was unable to complete a trade deal with the U.S. while it remains in the transition period.
With just one year to go until the United Kingdom begins to extricate itself, Juncker said it was time for May to put more meat on the bones, by turning "speeches into treaties". "That is what it means to be part of this union".
In the speech May suggested Britain would commit to keeping some European Union regulations and standards while reserving the option to diverge in others.
He said Ms May's decision to leave the single market and customs union was "closing doors" to possible models of future co-operation.
He added that it was a "rather surprising idea" to think the European Union could accept convergence in some areas "and at the same time open up the possibility for divergence when there is a comparative advantage to be had" for the UK.
European Parliament's Brexit co-ordinator Guy Verhofstadt also called for more details from the Prime Minister.
Negative effects from the approach of Brexit were already apparent, the BDI pointed out, with Britain dropping from second- to fifth-most-important trade partner for Germany past year.
The Prime Minister gave a major speech on her vision for post-Brexit relations with the European Union at the Mansion House last week in a bid to make progress.
"We will keep making this point in the run-up to the European Council next week", Juncker told the European Parliament."We are expecting more clarity on the American side in the coming days and will continue to work with our partners to push for an exemption". But Barnier said it dealt with the realities on the ground.