Iran's declaration that it could increase its uranium enrichment capacity if a nuclear deal with world powers falls apart risks sailing close to the "red line", France's foreign minister said on Wednesday.
"It's always dangerous to flirt with the red line," French foreign affairs minister Jean-Yves Le Drian told Europe 1 radio on Wednesday.
But Le Drian said plans to save the nuclear agreement remained intact.
Tensions between Iran and the West have resurged since President Donald Trump pulled the United States out of the 2015 nuclear deal with Tehran last month, calling it deeply flawed.
Le Drian was speaking a day after Israel's leader urged France to turn its attention to tackling Iran's "regional aggression", saying he no longer needed to convince Paris to quit a 2015 nuclear deal between various world powers with Tehran as economic pressure would kill it anyway.