But the prime minister of Slovenia, the current holder of the EU presidency, said the impasse created by Ireland's referendum last week should not slow the process of enlargement.
Turkey and Croatia are currently negotiating their accession to the European Union, with several other countries in the Balkans forming a queue to join too.
Sarkozy has long expressed his opposition to Turkey joining the bloc, even if the prospect remains many years away.
"No Lisbon (Treaty), no enlargement," he told reporters on Thursday, at the end of a first day of an EU leaders summit in Brussels dominated by discussions of the Irish vote.
The Lisbon Treaty was agreed last year by leaders after years of wrangling over how to make the EU more manageable but needs approval by all member states to come into effect.
"I would find it very strange for a Europe of 27 (countries) that has trouble agreeing on workable institutions to agree on adding a 28th, a 29th, a 30th, a 31st, which would definitely make things worse," Sarkozy said.
France is due to take over the EU presidency on July 1.
Croatia is furthest along the road towards joining the EU among candidate countries and it hopes to conclude negotiations next year.
Janez Jansa, prime minister of current EU president Slovenia, which neighbours Croatia, said the Irish vote should not set back the enlargement calendar.
"Basically, I don't think there is any reason for those candidate countries which have been fulfilling the rules and have been negotiating for accession should slow down the process," he told reporters.
"I don't see any reason why we should focus on enlargement issue here. This should not be a victim," Jansa said.
Czech Prime Minister Mirek Topolanek said he expected negotiations with Ireland on what it might do regarding the Lisbon Treaty would take place in the first half of 2009.
The Lisbon Treaty was designed to give the bloc stronger leadership with a long-term president of the European Council of EU leaders, an enhanced foreign policy supremo with a real diplomatic service, easier decision-making rules and a greater say for the national and European parliaments.
Concerns about enlargement were cited when French and Dutch voters in 2005 rejected an EU constitution that was later reworked into the Lisbon Treaty.
