People in the UK have been asked to ease off rushing to get Irish passports after the Brexit vote.
Minister for Foreign Affairs Charlie Flanagan said an "unnecessary surge" is threatening to have a significant impact on the passport service and could hit those who urgently need one.
"The increased interest clearly points to a sense of concern among some UK passport holders that the rights they enjoy as EU citizens are about to abruptly end," he said.
"I want to state clearly that this is not the case."
Mr Flanagan's intervention follows a spike in applications in recent days as well as inquiries about moving to Ireland after last week's shock EU referendum result.
One in four people in Britain has Irish heritage.
Post Offices in Northern Ireland ran out of Irish passport applications over the weekend.
Among the unlikely proponents for signing up to Irish citizenship was Ian Paisley Jnr Democratic Unionist Party MP and prominent Leave campaigner.
"My advice is if you are entitled to a second passport then take one," he tweeted.
My advice is if you are entitled to second passport then take one. I sign off lots of applications for constituents https://t.co/oWoiVIFF8A— Ian Paisley (@ianpaisleymp) June 24, 2016
But Mr Flanagan urged calm, stating UK passport holders would continue to enjoy EU rights for the "foreseeable future" until a formal exit was negotiated.
"An unnecessary surge in applications for Irish passports will place significant pressure on the system and on turnaround times and is likely to impact those with a genuine need for passports to facilitate imminent travel plans," he said.
"I urge those who believe they need to apply for an Irish passport immediately to enjoy free travel in the EU, to take full account of the facts before making an application."
The EU referendum result has not in any way changed the entitlement to an Irish passport for those eligible, he added.
On Friday, GoogleTrends said UK searches for "getting an Irish passport" jumped more than 100% after the Brexit result came through.
Most interest was shown in Northern Ireland, with the normally unionist heartland of Holywood, Co Down, taking top spot.
Irish senator Neale Richmond urged passport officials to be ready for the so-called Cascarino effect, recalling Jack Charlton's tactic of picking British footballers with Irish heritage when he managed the Republic of Ireland.
Mr Richmond, who has two English cousins who recently applied for Irish passports, said: "British citizens with Irish grandparents applying for Irish passports could now move from a torrent to a flood."