Platini was taken to hospital for tests as a precaution and according to UEFA sources was “fine” but had been suffering from flu.
A UEFA source said: “Michel has had flu for a couple of days and he fainted in a restaurant and was taken to hospital.
“He is having some tests but is conscious and well.”
There had initially been fears that Platini had suffered a heart attack but according to the UEFA source, that was not the case.
William Gaillard revealed the test results had shown up nothing serious.
“I talked to his assistant who was with him a few minutes ago and it seems (he was) just fainting because he has a cold and a fever,” Gaillard told Sky Sports News.
“All the preliminary exams are negative. He’s conscious, he’s fine.
“They may carry out more tests because when a well-known person faints they normally do that but I’ve been told not to worry. It’s nothing serious.”
On the reports Platini had suffered a heart attack, Gaillard added: “When people faint, people imagine the worst. That’s a normal human reaction. I talked to someone who told me not to worry. Nothing serious. These things happen.
“It’s cold there. A lot of people have a cold, the flu, they have a fever. That could explain it.”
Gaillard added he did not know whether Platini would be kept in hospital overnight.