Carolina Klüft's party was invited by sponsor Reebok, who had rented a terrace on the second level to celebrate the Swedish victory.
Carolina's two sisters, Martina and Sofia, had just taken the elevator down to the first level when the incident happened.
A man in his 30s had climbed across a fence higher up and jumped down from it. He landed by the elevator doors just as the sisters came out from the lift, Expressen reports.
"We heard a big bang just as we came out of the elevator. I did not look properly at first, but I saw that the man was hanging across a beam", Martina said.
Another man climbed down and got the man loose. As Carolina Klüft heard the news she screamed holding her hands across her mouth.
According to French police the man was still alive on Monday night but they are uncertain whether he will survive.
The police do not know why the man jumped. The number of suicide attempt from the Eiffel Tower is sinking each year due to improved security.