French presidential frontrunner Emmanuel Macron on Monday took aim at the course Turkey has taken under President Recep Tayyip Erdogan, who recently won a controversial referendum greatly expanding his powers.

Macron, the centrist candidate who faces far-right leader Marine Le Pen in France's May 7 second round, said if elected he would ensure France protected "democrats in all countries".

"I regret very deeply the route Turkey is taking, and I disapprove of it," the former economy minister told reporters at an event in Paris commemorating the Armenian genocide.

Turkey vehemently rejects the use of the term genocide to describe the mass killing of Armenians during World War I, arguing the episode was a collective tragedy in which both Turks and Armenians died.

France officially recognised the event as a genocide in 2001, a move that has soured relations with Ankara ever since.

The day after Erdogan won the disputed referendum on expanding his powers, Macron said there would be "no progress" in Turkey's EU accession talks if he became French president.

He said the referendum marked "an authoritarian drift" by the Turkish authorities.