The DUP's Ian Paisley Jr has accused the Tánaiste Simon Coveney of using "unnecessarily aggressive language".
It comes amid the continuing reaction to Boris Johnson's first House of Commons address as British prime minister.
On Thursday, Boris Johnson laid out his Brexit plan, including his insistence that the backstop be abolished in any Brexit deal.
However, that demand was swiftly rejected by EU and Irish leaders.
Speaking during a visit to Belfast yesterday, Mr Coveney said Mr Johnson's speech marked a "very bad day" in Brexit negotiations.
The Tánaiste said: "[Boris Johnson] seems to have made a deliberate decision to put Britain on a collision course with the European Union and Ireland in relation to the Brexit negotiations."
In comments quoted by the Belfast Telegraph, Ian Paisley Jr has accused Minister Coveney of using "unhelpful and unnecessarily aggressive language", while claiming the Irish government should dial down "megaphone diplomacy".
The DUP MP said: “It is high time Simon Coveney showed some respect for the constitutional situation.
He suggested the Irish government is entitled to speak its mind, but to do it in Stormont is "provocative and disrespectful".
Meanwhile, the Taoiseach Leo Varadkar warned Mr Johnson yesterday evening that the new British prime minister will have to row back on some of the things he has said in recent days if he truly wants to secure a Brexit deal.