Up to 100 demonstrators gathered outside Leinster House to protest against British prime minister Boris Johnson's visit to Dublin.
The protest was led by Seamus McDonnell from Co Armagh who chanted: "No customs, no border, no Brexit. "
Sinn Féin councillor Dessie Ellis said: "We want to send out a strong message that we will not stand for a hard border or any border.
"There are people from all around the country here to tell him that today, but particularly from the border region," Mr Ellis said.
Protester Fergal Donnelly, from Co Tyrone, said Mr Johnson "is hell bent on pursuing a no-deal Brexit".
"Our message is Ireland will not be collateral damage. Boris Johnson can pursue his own strategies in his own country but we are not going to be dragged out of the EU.
“Safety and prosperity for citizens north and south of the border won’t be compromised while we are here,” Mr Donnelly said.
Protester Marie Barry, from Co Cork, said: "I believe Boris Johnson is using our city as a commute stop to try and convince the people across the water in England that he is trying to get them a deal. He is not."
Mr Johnson said he wants a Brexit deal by October 18th and that he is undaunted by attempts by the British parliament to block a no-deal exit.
He said it should be possible for Britain to leave the EU while preserving the unchecked movement of people and goods across the Irish Border, maintaining the Belfast Agreement and protecting the economic unity of the island of Ireland. – PA