Mr Coveney said such a move would essentially see the implementation of a hard border on the island of Ireland and Dublin frozen out of the EU’s single market.
He said: “We would be taken out of the single market by default.
“The protocol is not just about Northern Ireland; it is about the island as a whole functioning as it needs to function in order to protect relationships and trade.”
The foreign affairs chief suggested the border plan was designed as much in London as it was in Brussels, “but many people seem to conveniently forget that”.
To keep the Irish border open, Northern Ireland effectively remains part of the EU’s single market and some checks are now made on some products arriving from the rest of the UK.
Mr Coveney said he was genuinely concerned about attempts to disrupt the Brexit border plan.
He added: “Despite the fact that I have become somewhat of a bogeyman for some people in the context of the protocol and trying to tell people the truth about it, the irony is that the Irish government, and my office in particular, has been constantly talking to the European Commission about the need for flexibility, the need to understand the tensions in politics in Northern Ireland because the protocol and its implementation, and the need for pragmatism in terms of implementation.”
Earlier this month, Downing Street sparked fury after it announced plans to unilaterally scrap the introduction of new border checks of food, parcels and pets between Great Britain and Northern Ireland.
It also moved to ease red tape on some fruit and veg amid fears supermarket supplies could soon run dry.
Brussels is expecting the publication of a “roadmap” today, outlining Britain’s plans to implement the border agreement fully.
No10 will still press on with plans to unilaterally extend the grace periods on EU red tape for Northern Ireland while talks continue.
The new, UK-only, measures are now due to expire on October 1.