A senior EU official says an attempt to trigger Article 16 of the Northern Ireland Brexit protocol was a mistake.
However, Maros Sefcovic said it should be viewed in the perspective of the EU's long track record of supporting Ireland.
He said the issue arose as the EU was concerned it was not 'always getting its fair share' of COVID-19 vaccines produced in the bloc.
Triggering the article could have meant checks on goods moving between Northern Ireland and the Republic.
The EU said last month floated the idea of using the article to ensure vaccines were not leaving the EU through Northern Ireland.
Amid the bloc's row with AstraZeneca over vaccine supplies, the Article would have temporarily placed export controls on the movement of vaccines.
However, the EU quickly backed down after an immediate backlash from Ireland and the UK.
It prompted European Commission President Ursula von der Leyen to admit mistakes were made.
European Commission Vice-President Maros Sefcovic today told an Oireachtas committee that lessons have been learned.
He said: "The bottom line is that the mistakes were made in the process leading up to the decision, and we deeply regret that.
"In the end, in the matter of three hours, we got it right - Article 16 was never activated.
"I can reassure you that the European Commission has learned the lesson, and the Commission will do the utmost to protect the peace in Northern Ireland."
He added that the EU is fully committed to the implementation of the Brexit deal's Northern Ireland Protocol.