Brexit has put the Irish peace process at risk, Germany's foreign minister warned on Thursday ahead of a meeting with James Cleverly.
Annalena Baerbock told Britain it had a responsibility to "protect and to implement" the Northern Ireland Protocol before meeting the Foreign Secretary on Friday.
Mr Cleverly had earlier suggested that German commitment to the Protocol as it stands might not be as uncompromising as Berlin insists.
"Brexit was and is a watershed for us all. That applies particularly to the relationship between the United Kingdom and Ireland due to the division of the island of Ireland," Ms Baerbock, who is holding talks with the Irish foreign minister in Dublin before Mr Cleverly, said.
"It was only in 1998 that the Good Friday Agreement brought peace after more than 30 years of violent conflict in Northern Ireland," she said.
"This peace, the fact that hostilities have ceased and both Catholics and Protestants in Northern Ireland can once again live alongside one another in a spirit of good neighbourliness must not be jeopardised under any circumstances."
'Reopening of old wounds'
Ms Baerbock added: "Yet precisely this is at stake as a result of Brexit and its consequences for trade, freedom of movement and other issues."
Ms Baerbock said the Protocol prevented "a hard border on the island of Ireland and thus also the reopening of the old wounds".
She added: "All of us - in the EU member states and in the United Kingdom - have a responsibility to protect and to implement the Northern Ireland Protocol."
Her comments will be seen as a response to an interview Mr Cleverly gave to Die Welt before the German minister's visit.
He said Germany's strong commitment to the Northern Ireland Protocol was "an avatar".
"I think often what people say they want and what people actually want are subtly different", he said.
EU nations angered by Protocol Bill
Germany's government signed a coalition agreement which explicitly states that the Brexit agreements and the Northern Ireland Protocol had to be "fully implemented".
Berlin, like other EU capitals, was angered by British threats to unilaterally tear up the Irish Sea border treaty with the Northern Ireland Protocol Bill.
The EU has warned it will retaliate if the legislation is used, with suggestions it could spark a trade war by imposing tariffs on British goods.
The Protocol created the Irish Sea border for British goods entering Northern Ireland but prevents a hard land border with EU member Ireland. It also gives Northern Ireland dual access to both the UK and EU markets.
The Government wants to reduce the number of border checks on British goods in negotiations with the EU but has threatened to use the Northern Ireland Protocol Bill if a deal cannot be negotiated.
It also wants an end to the influence of the European Court of Justice in Northern Ireland, which is rejected by Brussels and other EU capitals.
Technical talks continue but Mr Cleverley, the UK's negotiator, is yet to hold formal political negotiations with the European Commission.
Friday's meeting in London will cover the Protocol, the war in Ukraine and strengthening ties between Germany and the UK after Brexit.
Mr Cleverly and Ms Baerbock will attend the first "UK-Germany Strategic Dialogue" held in London. Both will also speak at the Königswinter Conference, an event celebrating Anglo-German relations.