Floersch was catapulted off the track into a photographers' bunker after hitting the back of one car and shunted over another while travelling at more than 275 kilometres per hour (171 mph) on the tight street circuit.
The teenager was conscious when taken to hospital in the former Portuguese colony from where she tweeted that she was "fine" and would undergo surgery on Monday.
"After the serious incident today in Macau the FIA is mobilized to help those involved and analyse what happened," International Motorsport Federation (FIA) president Todt tweeted.
"We will monitor the situation and make the necessary conclusions."
Japanese driver Sho Tsuboi, who Floersch hit after the initial impact, was also taken to hospital complaining of back pain but the Macau Grand Prix Organising Committee said in a statement said he had been discharged after treatment.
Chief Medical Officer of the Macau Grand Prix, Dr. Chan Wai Sin, said two photographers and one track marshal were also injured in the crash and taken to hospital for treatment.
Crashes are frequent at the Macau Grand Prix which this year, in its 65th edition, hosted six car and motorcycle races on the 6.2-km Guia Circuit around the streets of the island.
Last year, British motorcyclist Daniel Hegarty died after hitting the safety barrier during a race, the eighth rider to have lost his life on the circuit since 1973.
Three motorcyclists were taken to hospital after crashes at the circuit this week with Britain Andrew Dudgeon requiring a metal rod to be inserted in his spine after a crash in practice.
Dudgeon comes from Britain's Isle of Man where 270 motorcyclists have been killed in competition on the island's TT circuits over the last 120 years.
(Reporting by Nick Mulvenney in Sydney; Editing by Amlan Chakraborty)
