French President Emmanuel Macron and German Chancellor Angela Merkel stressed that threats against the sovereignty of European Union member states are not acceptable during a meeting at Fort de Bregancon, in the south-east of France on Thursday.
The statement came against the backdrop of Turkish aggression to Greece and Cyprus in the Eastern Mediterranean.
The two leaders, who met to discuss major challenges facing the bloc, stressed the need for dialogue, with Macron saying they wished to show their solidarity with Greece and Cyprus.
He also expressed full French support for German mediation between Athens and Ankara.
The dialogue must start again, said Merkel, who added that a lot of tension has accumulated in the Eastern Mediterranean.