France called on Turkey on Friday to stop "illegal activities" in Cyprus's exclusive economic zone.
President Emmanuel Macron added that the European Union would not back down on the issue.
"I want to reiterate my solidarity with Cyprus and my support and respect for its sovereignty. Turkey must stop its illegal activities in Cyprus's exclusive economic zone," he said after a summit of Southern European Union heads of states in Malta.
EU members have pressured Turkey to drop its plans for offshore drilling for natural gas in an area claimed by the Cypriot authorities as part of their exclusive economic zone around the island.
"The European Union will not show weakness on this matter," Macron stressed.
Turkey and Cyprus have been at odds since the 1974 ethnic conflict that split the island between its Greek and Turkish Cypriot populations.
A Turkish drill ship, the Fatih, has been anchored west of Cyprus since last month, and another drill vessel, the Yavuz, is scheduled to be deployed east of the island soon.
Both areas are claimed by the Greek Cypriot government as its exclusive economic zone, where it has commercial rights to explore for hydrocarbons. Turkey maintains an area west of Cyprus is its own continental shelf.