"The European Commission, this Parliament and all other 26 member states will always show loyalty and solidarity with Ireland when it comes to the Irish border", Juncker said.
Juncker said in his state of the union speech to the European Parliament: 'The European Commission is today proposing to strengthen the European Border and Coast Guard to better protect our external borders with an additional 10,000 European border guards by 2020'.
Later, asked by the BBC whether he wanted the European Union to have superpower status, Juncker was cautious in his language.
In the parliamentary debate which followed his hour-long address, Nigel Farage, of the UK Independence Party, accused him of failing to acknowledge the arrival of eurosceptics in government in Italy and a "populist revolt" across Europe that he said would resist Juncker's aim to centralize more power. "Superpower, I don't like that expression".
"In the past months, whenever we needed unity in the Union, Britain was at our side, driven by the same values and principles as all other Europeans".
Juncker on Wednesday also called for placing the fight against terror within the jurisdiction of the future European Public Prosecutor's Office. "What we want is to become more autonomous and live up to our global responsibilities".
But Juncker's direction of travel was clear.
Apple expected to announce new iPhone, gadgets next month
The company could launch three new iPhones with 6.5 inch OLED display, 5.8 inch OLD and 6.1 inch TFT LCD display. So, if you love all things Apple , it seems September 12 is the date you definitely need to put in your diary.
Juncker expressed his disapproval of those who pursued unilateral actions, waging trade and currency wars.
But he appealed to heads of government to end the recent squabbling and divisive rhetoric and seize the moment rather than risk letting the continent slide into diplomatic conflict or worse. "We are out of time".
Mrs May responded in the Commons by saying: "I believe a deal that is right for the United Kingdom will be a deal that is right for the European Union". "Let us not sully it's image".
Delivering his annual state-of-the-union speech to the European Parliament, Juncker said the EU will not allow Britain to participate only in some parts of the bloc's single market after Brexit without honouring all of its rules.
"We've made significant strides finding and removing terrorist propaganda quickly and at scale, but we know we can do more", it said in a statement. 'We need a lot more. And we have to stop seeing this relationship through the sole prism of development aid.
But he said he Britain would remain a close ally of Europe, and urged both the government and European Union negotiator Michel Barnier to negotiate a strong trade partnership.