Nigel Dodds has urged Sinn Fein to take action against a TD who urged the EU to "aim above political unionism" on the Northern Ireland Protocol.
The DUP's deputy leader was speaking after European Commission Vice-President Maros Sefcovic appeared before the Irish Parliament's European Affairs Committee on Tuesday
Mr Sefcovic said the EU's commitment to the protocol was "unwavering" ahead of a visit to Northern Ireland on Thursday.
The protocol, part of the UK's Brexit deal with the EU, keeps Northern Ireland aligned with the bloc on trade rules to prevent the creation of a hard border on the island of Ireland.
It has angered unionists who claim the move has created a trade border in the Irish Sea and cut Northern Ireland off from the rest of the UK.
They have urged Prime Minister Boris Johnson to invoke Article 16 of the protocol which allows either side to suspend it due to difficulties.
A number of businesses have also reported trade problems since the protocol was introduced.
Addressing the committee Sinn Fein TD Ruairi O Murchu said that political unionism was "operating a playbook it used in the 1980s and the 1880s, and that is unfortunate".
"If the European Commission (the Executive branch of the EU) wants to sell the Irish protocol to businessmen and farmers from a unionist and nationalist background, it may need to aim above political unionism," the Louth TD said.
He also invited Mr Sefcovic to visit the border region.
Lord Dodds said the EU could make a mistake by taking Sinn Fein’s advice and closing its eyes to unionist concerns.
“Maros Sefcovic and his team know that not one single unionist party in Northern Ireland supports the protocol, yet the European Union claims to be a protector of stability and Belfast Agreement," he said.
The peer said "it would be another mistake for the European Commission to take the arrogant advice proffered by Sinn Fein".
"Sinn Fein talk about a shared future but their actions show their plan is one of ourselves alone," Lord Dodds said.
"This is not the first SF Louth TD to speak offensively about unionists, it was Gerry Adams who told supporters 'the point is to actually break these b****s - that’s the point.' Sinn Fein has form."
The unionist grandee called on Sinn Fein President Mary Lou McDonald to "censure" Mr O Murchu for his comments.
"Unionism will not be ignored or silenced," Lord Dodds said.
Mr Sefcovic told the committee that the EU "deeply regretted" threatening to trigger Article 16 after a recent row over Covid-19 vaccine supplies.
He said he believed solutions could be found to the issues being experienced around the protocol.
"We could do our best and we are working on it to minimise the negative impact on the people of Ireland and Northern Ireland," the European Commission vice-president said.
"But it was quite obvious from the beginning that there will be teething problems and I believe that we can resolve them if we work very well together."
On Tuesday evening, First Minister Arlene Foster said she had discussed the protocol with Northern Ireland Secretary Brandon Lewis.
"When Maros Sefcovic conducts meetings here on Thursday, the people he meets must include those hardest hit & those who opposed the protocol rather than just cheerleaders for the rigorous implementation of the protocol," the DUP leader said.