"It is a mistake to lead Turkey into believing that it can join Europe. We must have close relations with Turkey, common interests with Turkey. But it should not be a member of the European Union," Sarkozy told the Europe 1 radio broadcaster.
Turkey has recently resumed efforts for accession to the EU, with Prime Minister Ahmet Davutoglu attending an EU-Turkey summit on Sunday in Brussels. The summit will continue ongoing negotiations on Turkey's EU accession.
Turkey signed an association agreement with the bloc in 1963, and submitted a membership application in 1987. Talks began in 2005, with 14 of 35 necessary conditions for accession fulfilled so far by Ankara. The Cyprus dispute and Turkey's record of denying press freedoms are among major issues currently unresolved, and known to be obstructing Turkey's accession.
"When we decided to act in Syria, we did not assess the consequences of this decision for the domestic security," Sarkozy said.
He added that he approved of the operation, but that the aerial campaign in Syria increased the threat for the French territory.
France is carrying out anti-Daesh airstrikes in both Syria and Iraq as part of a US-led international coalition. Paris intensified its attacks after Daesh, prohibited in many countries, including Russia and the United States, claimed responsibility for the November 13 killings of 130 people in Paris.