Some 800 flag-waving Turks gathered in the eastern French city of Metz for the address by Mevlut Cavusoglu, who is campaigning for constitutional changes that would boost the powers of Turkish President Recep Tayyip Erdogan.
The "fascism" comment echoed accusations by Erdogan himself, both Saturday and again on Sunday, when he said the Netherlands was behaving like the Nazis in its treatment of Turkish ministers, AFP reported.
The Metz rally, which had the blessing of the French authorities, was planned weeks ago but took on "another dimension" because of the row between Ankara and The Hague, said Saban Kiper, vice president of a grouping in France of Turkish associations.
"France has a more serene attitude than the Netherlands," he said.
French Foreign Minister Jean-Marc Ayrault said in a statement there was "no reason to prohibit this gathering that... poses no possibility of interference in French political life."
However, Ayrault warned Ankara: "In the face of the current tension between Turkey and several member states of the European Union, France... urges the Turkish authorities to avoid excesses and provocations."
The Turkish community in France numbers around 700,000, including some 160,000 in the eastern region.