Centre back Dayot Upamecano (24) and midfielder Adrien Rabiot (27) missed Wednesday's 2-0 semi-final win over Morocco with the illness, but coach Didier Deschamps refused to panic.
"We don't worry about illnesses. In the past few days the temperatures in Qatar have fallen a little bit, the air-conditioning is on and we have cases of flu-like symptoms and we're careful it doesn't spread," he said on Wednesday.
"Players have made great efforts on the pitch and suffered immediately after the match, the body is weakened and you're more prone to be infected by these viruses. We're taking necessary precautions."
Striker Randal Kolo Muani (24), who came off the bench to score France's second goal in their win over Morocco, said on Friday: "There's a little flu that's been spreading but nothing serious. They'll be well soon and be ready for Sunday."
A French press officer added: "As you know, Randal is not a doctor, we will communicate about it later."
A French press officer added: "As you know, Randal is not a doctor, we will communicate about it later."
Kolo Muani said the players who fell ill had been isolated.
"Those who are sick stay in their room, they're being taken care of by the doctors and we've been enforcing social distancing. We're very strict about it," he said.
Forward Ousmane Dembele said: "We're not scared of that virus. Dayot and Adrien got a bit of a stomach ache, I made them a ginger and honey tea and then they felt better. I hope everyone will be ready for the final.
"Dayot got better and I think everyone will be ready. We've been taking precautions. The first day, Dayot stayed in his room and we brought him food and he was back with everyone the next day."
France midfielder Aurelien Tchouameni (knock on hip) and Theo Hernandez (knock on knee) missed training on Friday to work indoors, FFF said.
Deschamps was confident both Upamecano and Rabiot would be fit for Sunday's showdown at the Lusail Stadium.
"Dayot will be fit. Since Saturday he wasn't well for three days ... had a fever and that had an impact on his strength," he said.
"Given the tough match we had I decided not to play him and play Konate instead as he's shown he's good enough to play at this level.
"Rabiot was sick, was better this afternoon but not well enough so he stayed in the hotel. We have four days to rest so he should be better and available for Sunday."
Should Konate and Varane be out, however, Deschamps would face a difficult selection decision, as he would be without two of his top three defenders.
