Former Workers' Party and Democratic Left leader Proinsias De Rossa has called on politicians to "step back" from the "explosive" idea of a border poll.
The former Irish government minister said he agreed with Taoiseach Micheál Martin that now is not the time to hold a poll.
"Why in heaven's name should we contemplate or prepare for a border poll when there are still 100 walls dividing the community in Northern Ireland?" he wrote in a letter to the Irish Times.
"When the 'new' IRA plants a bomb trying to slaughter a young woman and her child in the name of 'the noble aspiration of unity'.
"Surely community reconciliation in Northern Ireland is the urgent task we should be engaging with as a 'noble aspiration'?"
Mr De Rossa said the Good Friday Agreement "embedded a constitutional settlement for peace on this island fit to last for the next 100 years and more".
"But only if the political leadership in Northern Ireland, Westminster and the Oireachtas harness it to the task of reconciliation rather than trying to outflank each other."
His comments come after a survey found that more than a third of people across Ireland believe a border poll should be held within the next five years.
A LucidTalk and Ireland Thinks poll found that in the north, 37 per cent of respondents thought a referendum should take place within five years and 29 per cent at some point after that.
The findings were part of a survey commissioned for BBC Northern Ireland’s Spotlight programme.
Fine Gael TD and former justice and foreign affairs minister Charlie Flanagan agreed with Mr De Rossa's comments and said more work must be done on peace and reconciliation in Northern Ireland before a border poll can be held.
Mr Flanagan tweeted yesterday: "Lots of hard work & endeavour required along the road to peace & reconciliation before any Border poll should be contemplated".
Ulster Unionist Peer Lord Empey said it was "fanciful" to suggest there is strong support for a united Ireland on either side of the border.
"The terrible attack on a young family at Dungiven this week should bring all politicians to their senses," he said.
"There, in the pursuit of a so called 'United Ireland', terrorists were quite prepared to murder a mother and her young child.
"What kind of country are they trying to create from such vile acts?
"Who do they think would ever want to live in it? There isn’t much sign of a shared island from these fascists."
