Nato's Isaf force did not provide details, but Afghan officials say the four were French soldiers based in Kapisa province.
Taliban insurgents said Saturday ' s attack was carried out by one of their suicide bombers.
France is due to withdraw all its combat troops by the end of this year, two years before the main Nato pullout.
Violence has risen across Afghanistan in recent weeks, with the Taliban vowing to target both the Afghan forces and the ۱۳۰,۰۰۰ foreign troops remaining in the country.
Afghan officials say the suicide bomber in Saturday ' s attack approached a French Nato convoy wearing a burka.
France is currently the fifth largest contributor to the Isaf force, with nearly ۳,۳۰۰ French soldiers stationed in Afghanistan.
The deaths - if confirmed - would bring to ۸۷ the total number of French deaths in the country since ۲۰۰۱.
In January the killing of four French soldiers in Kapisa prompted then - President Nicolas Sarkozy to announce a withdrawal by the end of ۲۰۱۳.
His successor Francois Hollande, who was elected last month, confirmed an election pledge to bring the pullout forward by a further year.
