Taoiseach Leo Varadkar fears the controversy over the botched plan to commemorate the Royal Irish Constabulary (RIC) is a "setback" to a united Ireland.
His remarks came as Culture Minister Josepha Madigan faced criticism amid claims that the Government is failing to make preparations for state commemorations as the Decade of Centenaries enters the sensitive years of the War of Independence and Civil War.
Members of a cross- party group criticised the minster for holding only four meetings of the body since she assumed the role in 2017.
Justice Minister Charlie Flanagan postponed the ceremony to commemorate the RIC and the Dublin Metropolitan Police (DMP) after a fierce backlash.
He was forced to deny the event would commemorate the notorious Black and Tans sent by the British government to back up the police.
Mr Varadkar said it was the right decision to defer the gathering, but also hit out at opposition politicians for misrepresenting plans for the commemoration in Dublin Castle.
He admitted there were "lessons to learn" and expressed hope the event would take place at a later date "in a way that's more appropriate and allows us to consult with the opposition and with others".
He said he firmly believes in a united Ireland and that it is possible in his lifetime, but fears it has been delayed as a result of the row.
He said there must be a recognition of the unionist tradition in Ireland.
Mr Varadkar said there were victims as well as perpetrators on both sides, and this shared history had to be embraced and understood if there was to be a united Ireland.
He said it was his "deep regret" that "moving towards a united Ireland feels to me to be a little bit further away than before".
Fianna Fail's Eamon O Cuiv said: "The anniversaries have come up very fast and there hasn't been adequate discussion as to how we're going to deal with them in a balanced and respectful way."
Earlier this week, Fianna Fail leader Micheal Martin said the planned RIC/DMP commemoration was an "error in judgment".
He said the Government caused "unnecessary controversy" by abandoning the approach of seeking public consultation and seeking advice from the head of commemorations.
He said both police forces should be remembered, but said the controversial event was "not the appropriate vehicle".