The Taoiseach has said a border poll won't be on his government's agenda for at least five years.
Micheal Martin made the comments during a speech at Dublin Castle yesterday morning in which he set out his strategy for a shared future across the island of Ireland.
Mr Martin sought to reassure unionists about the work of his new Shared Island Unit.
Asked by Belfast solicitor Sarah Creighton why unionists should engage with the project, Mr Martin replied: "The government has said that for the next five years a border poll is not on our agenda. I've made that clear.
"Some people don't like that, (but) I've made it very clear that it's not on our agenda for the next five years.
"I've also made it clear that my approach is through consensus and listening and engagement. I am very much taken by the Seamus Mallon view."
He said that when he met the former deputy leader of the SDLP before he passed away, Mr Mallon told him it was "about time we started sharing this place together".
"That's informing my thinking. Unionists, from my experience, get the necessity and importance of engagement north-south," Mr Martin added.
"There is no, I get the sense, ideological opposition to the idea of working north-south while respecting people's identity and constitutional perspectives.
"(It's about) having that space to enable them to engage without having any political fallout or repercussions arising from that engagement.
"We want to create opportunities through the unit where both civic unionism and political unionism can (have an) input."
A pledge by the Taoiseach to spend €500million on cross-border projects by 2025 was welcomed by Stormont's Infrastructure Minister.
Nicola Mallon praised what she called a "shared vision" on all-island infrastructure projects, such as Narrow Water Bridge, the A5, and the Ulster Canal. "As the island of Ireland faces the unprecedented challenges of Covid and Brexit, never before has the need for partnership, working across our country to deliver these projects, been (more pronounced," she said.
Mr Martin said there would be review work on the viability of high-speed cross-border rail.
On outstanding infrastructure projects, he said his government was ready to work with Stormont "without undue delay".
Mr Martin said the Irish government's Shared Island Unit was about building consensus.
"As Taoiseach, I respect and I affirm everyone's right on the island to make the case for the constitutional future they wish to see for Northern Ireland, whether they are nationalist, unionist or neither," he added.
He said the "genius" of the Good Friday Agreement meant people no longer had to be "defined or dominated" by the constitutional question.
"We can all work together for a shared future without in any way relinquishing our equally legitimate ambitions or beliefs," Mr Martin explained.
After growing up with "a negative attitude of Britain's role in Northern Ireland," he said his view had evolved over time.
"You need to stand back from prejudices and back from the rhetoric and simplistic narratives and move beyond all of that and get down to pragmatic engagement," he insisted.
Mr Martin added that he was "wedded" to the core of the Belfast Agreement.
"That's about unifying hearts and minds. It's about developing a sense of community in people. It's not territorial to me - it never was," he said.
Alliance MP Stephen Farry welcomed the Taoiseach's speech, saying it created "major opportunities" to improve cooperation and partnership across the island of Ireland.
Sinn Fein leader Mary Lou McDonald, however, said Mr Martin's decision not to pursue a border poll for at least five years was "disappointing".
"It is a mistake to think that we can unify the people of this island while retaining the division that the border has cemented for generations," she said.
"It certainly won't be achieved by pushing back against a referendum on Irish unity."