Israel and Lebanon have technically been at war since 1948, and Lebanon boycotts its southern neighbour.
"I love and respect Elie Saab, but is he really happy an Israeli actress wore a dress he designed?" asked Lebanon journalist Heba Bitar on Twitter.
The picture of Gadot has since been removed from Saab's Instagram account.
The image of the Wonder Woman star in a blue sash dress by Saab and was accompanied by a description of the former Israel Defense Forces combat trainer as "flawless".