"This is no joke. It's not some movie. People are dying."
The coronavirus has France extending the rule's duration.
There has been controversy about footwear rules at Cannes Film Festival after women in flats were allegedly denied entry to a screening in 2015.
William Oldroyd's film, acclaimed on the festival circuit for its daring, is joyless, ugly and arguably racist.
Miri Regev's dress emblazoned with the contested city's skyline turned heads at festival's opening, leading to viral mock-ups.
Wolf and sheep is the debut feature film by Afghan filmmaker Shahrbanoo Sadat.
The 69th edition of the festival in south France will run from May 11 to 22.
Several women were turned away from the screening of 'Carol' for wearing flat shoes.