The Taoiseach has said he believes the dispute over the Northern Ireland Protocol can be resolved with a ''pragmatic commonsense approach''.
Speaking on CNN's 'Quest Means Business', Micheál Martin said he has made it clear to the British Prime Minister Boris Johnson that on and off unilateralism doesn't work.
He is "concerned" that there is an increasing trend from the British government of more unilaterialism on different aspects that impact the Good Friday agreement.
The Taoiseach said that is "not positive development" and he would Britain to be "conscious of the necessity for a partnership approach" where as co-guarantors of the agreement.
Mr Martin added that he finds it "unconscionable" that the Stormont assembly is prevented from meeting at the moment, adding that it was a "denial of democracy".
He told CNN the Irish view is that the operation of the protocol can work but ''there has to be a serious engagement to make it happen''.
It follows a discussion today between the Taoiseach and EU Commission President Ursula von der Leyen.
Mr Martin commented: "We are fully aligned on the need for joint solutions on the protocol – unilateral action is not helpful."
Ms von der Leyen noted: "The EU and Ireland are on the same page: International agreements cannot be disapplied unilaterally. The UK needs to work with us to find joint, workable solutions."
Earlier, the European Union's ambassador to the UK warned that Brussels will not change its mandate and reopen negotiations on the Northern Ireland Protocol.
Joao Vale de Almeida told journalists he could not see a "happy ending" to the impasse at present.
British Foreign Secretary Liz Truss has urged the EU to change its mandate so that the protocol can be fundamentally rewritten.
However, EU ambassador Joao Vale de Almeida told journalists at a Westminster lunch: "We were told that we should get a new mandate but I can tell you very clearly what the member states are telling us is very simple: You don't need a mandate and even if you ask for one, you will not get it."
He said there was a lack of trust between the two sides and there was little sign of a "happy ending" in the protocol row.
"I'm worried by the low levels of trust that exists today between the EU and the UK, between our leaders, between all of us that are involved in this relationship," he said.
He compared the protocol rows to a long-running drama: "I was hoping to see in this season of this saga ... more creativity and hopefully a happy ending.
"I'm not seeing it for the moment and this is an area where I think things have not changed enough."
Mr Vale de Almeida said there was "untapped potential" in the proposals Brussels had put forward to resolve the row over Northern Ireland's post-Brexit arrangements.
He said: "The potential of those proposals is not yet exhausted. There is untapped potential in those proposals for us to find the solution - provided that we are focused on finding the solutions."
The EU "is committed to contribute to solutions for the problems that we recognise exist in implementing the protocol, but we cannot renegotiate the protocol".
"The ink of the signatures is hardly dry," he said. "We negotiated for a long time, there is no real alternative to it."
The solutions to the issues had to be found "within the limits of the protocol", he added.
Mr Vale de Almeida said the row over the Northern Ireland Protocol was having an "excessively negative" impact on the overall relationship between Westminster and Brussels.
"If I look at the wider picture of our relationship, our problems with the Northern Ireland Protocol have an excessively negative impact on the quality of our overall relationship and we need to overcome this situation."
British Prime Minister Boris Johnson has insisted of his plans for the protocol "we don't want to nix it, we want to fix it".
But the ambassador said: "It's not very reassuring if you go into a negotiation where you are presented with two options - either renegotiation or unilateral action to override the treaty.
"This is not the best way to fix, this is rather a way maybe to nix.
"So if we want to fix it, which is what we want and I understand this is what the Government wants as well, we need to create a better atmosphere."
He warned that unilateral action by the UK government would provoke a response from Brussels.
"Is that what we want, an escalation around Northern Ireland at this present point in time? I don't think so," he said.
Downing Street said the EU's proposals for fixing the protocol did not "address the problems that we know exist on the ground".
A spokesman for Boris Johnson said: "You will know that we have invited vice-president (at the European Commission, Maros) Sefcovic to London to hold further talks.
"The Foreign Secretary has been clear that the measures that are currently on the table won't address the problems that we know exist on the ground in Northern Ireland, which is why we need to find new solutions.
"We remain committed to trying to reach a negotiated settlement."
