President Michael D Higgins has warned about the growth of racism and xenophobia and its threat to democracy.
At a ceremony for the diplomatic corps in Dublin, Mr Higgins also raised concerns about the negative impact of Brexit on the North.
"In Europe and the United States deepening inequalities have betrayed the commitment to cohesion upon which so many hopes have been placed," he said.
"Racism and xenophobia are gaining ground, exploiting fears and ignorance in ways that could destroy democracy itself."
He also used his address at the annual new year welcome ceremony in Aras an Uachtarain to raise awareness of the migrant crisis and warn that the United Nations was inadequately funded and disconnected from citizens who rely on its moral authority.
"More worryingly still, it is attacked on occasion by the most powerful, and frustrated in its moral purpose by the blatant pursuit of interests," he said.
Mr Higgins said Northern Ireland was a living example of the positive impact of EU membership.
"Recent political developments have resulted in an election in Northern Ireland and there is a risk that old divisions may come to the forefront in the upcoming campaign.
"This combines with concerns about the impact of Brexit on a region which, while transformed over the past two decades, is not yet fully reconciled or healed and should remind us again, as if we needed it, of the relative fragility of peace."
Mr Higgins said the people of Northern Ireland expect their politicians to work together effectively to fulfil the promise of the Good Friday Agreement.
"That democratic endorsement is a powerful one which reminds us that - even in times of difficulty - we have a duty of hope," he said.