An editorial described Mr Ahern's government as "absent from the debate" that preceded the referendum but was confident a way out of the impasse would be found.
Many newspapers noted that Ireland has done well from EU membership and were critical of Prime Minister Bertie Ahern's failure to make a good case for a Yes vote.
"The best pupils of the European class have spat in the soup... The blow is all the more treacherous in that it comes from a country that owes its new wealth to Europe," France's centre-left Liberation commented.
An editorial described Mr Ahern's government as "absent from the debate" that preceded the referendum but was confident a way out of the impasse would be found.
"The imagination resources of the shameful fathers of the limping treaty may not be infinite, but they are large," it said.
Slovenia's Delo launched a scathing attack on the reluctance of EU countries to accommodate their eastern neighbours.
"One would expect the students to be the ones to blush in the enlargement process because they cannot cope with the high goals set by Brussels," it said.
"Surprisingly... it is not the reforming countries that are in trouble but the teachers of the new European democracy, who are unwilling to change a single comma for the benefit of a different Europe."
Paralysis
Madrid's El Pais criticized the EU decision-making process.
"It is paradoxical that half a million votes - cast in a referendum with a close result and the lowest turnout in Irish history - could stop a treaty coming into force which affects 370m people and the hopes of millions of others who want to join the EU."
It concluded that "the EU must agree systems for changing its rules so they cannot be paralysed by a single state. Otherwise, a European Union of 27 or more members will be ungovernable."
France's Le Figaro made a similar point.
It noted the "communications shortcomings" of EU institutions, lack of transparency and the paralysis engulfing decision-making mechanisms originally set up for a community of six.
"The game has simply become too complicated," it said.
Warning
Portugal's Publico argued that the referendum had a "silver lining - the warning it represents".
Europe must confront the "persistent apathy" of its citizens and face up to growing mistrust and scepticism in many countries, it said.
Several commentators in Germany and Austria dwelt on the failings of the Nice Treaty and saw the Irish vote as an opportunity for a rethink.
"The Irish didn't know what to make of the Nice Treaty and what it would make of the European Union.
"Why? Because the EU... no longer knows what it is and what it wants to be. Ireland has therefore posed the question of all questions. Thank you," a Die Welt commentator said.
In Austria's Kurier, a Social Democratic MEP described the vote as "a victory for democracy" and a "resounding slap in the face" for "highhanded government leaders" who had cooked up an unacceptable deal behind closed doors.
He concluded it gave Europe a "wonderful chance" to find true democracy and make careful preparations for eastward expansion.
BBC Monitoring, based in Caversham in southern England, selects and translates information from radio, television, press, news agencies and the Internet from 150 countries in more than 70 languages.