The DUP leader has said Leo Varadkar set a precedent that has led some loyalists to contemplate violent resistance to the Brexit deal.
Arlene Foster pointed to the Taoiseach's warnings about the potential for increased dissident republican violence if Brexit led to a hardening of the Irish Border, calling his comments "wrong".
Ms Foster made the remarks while addressing fears about possible loyalist disorder if Brexit creates economic barriers between Northern Ireland and the rest of the UK.
PSNI chief constable Simon Byrne is among those who have voiced concern at the prospect.
When asked about the issue ahead of her party conference this weekend, Ms Foster suggested Mr Varadkar’s words had been a contributory factor.
“Of course any violence or threat of violence should not be adhered to,” she told the PA news agency.
“When Leo Varadkar talked about the possibility of dissident violence along the Border, if there were any Border infrastructure . . . I thought that was wrong. I said so at the time.
“Because you can’t use the threat of violence to achieve something.
“And that unfortunately now has set a precedent where people from loyalism are looking at that, and they’re saying: ‘Hold on a second, he used that in that particular way, so now we’re going to use that.’
“That’s wrong. That is not the way forward.”
‘Understandable concerns’
Ms Foster said loyalist concerns about the Brexit deal were understandable.
“I am not dismissing, and I want to be very clear on this, fears and concerns of the loyalist community, or indeed unionist middle-class people, or anybody in unionism at the moment, because actually unionism and loyalism are all at one relation to this deal — they are rejecting it,” she said.
“So instead of talking about loyalist violence in relation to that, let’s deal with those fears.
“And let’s deal with those concerns in a way that addresses them.
“And the way to do that, of course, is to try and deal with those issues around [democratic] consent and the concerns that we have around customs.”
In response to Ms Foster’s remarks, a spokesman for the Taoiseach said: “The Irish Government is a co-guarantor of the Good Friday Agreement.
“Protecting peace on the island of Ireland has [been] and always will be our overriding objective.
"It should be clear to everyone that Brexit itself has disturbed the political equilibrium in Northern Ireland.
“It’s the main reason why the Irish Government was against it.
“We have never wanted any new borders neither North-South nor in the Irish Sea.
“Unfortunately, leaving the EU customs union and single market requires that checks must now happen somewhere.” – PA
