Speculation had been rife that Schumacher might make an early comeback in Sunday's race after suffering a double fracture to his right leg at the British Grand Prix in July.
However, a Ferrari statement read: "Michael Schumacher will be testing next week at Monza for the Italian Grand Prix. During the session, which will run from 1-3 September, he will also simulate a race, with the objective of competing in the Italian Grand Prix."
Schumacher's spokesman, Heiner Buchinger, said that the decision had been taken in conjunction with the driver because he had suffered from acute pains in his leg since Monday. Buchinger said: "It's simply not going well. Since Monday, it has been going worse."
The optimism over Schumacher had flourished after the German put in a demanding practice session aboard his F399 at Mugello last Friday. But he suffered pain in his ankle after completing 20 laps at full tilt. Over the weekend, the pain also prevented Schumacher from fully completing a physical training programme which he had set himself.
The Italian team have therefore decided to give his stand-in Salo another drive alongside the World Championship leader Irvine, before Ferrari's home race at Monza on 12 September.
Jean Alesi, the French driver, will drive for the Prost team during next year's Formula One World Championship. Alesi, who has won one Grand Prix (in Canada in 1995) in over 160 races, has scored just one point this season and was forced to retire from the Hungarian Grand Prix.
Alesi announced that he would be leaving the Sauber team at the end of the season and Alain Prost yesterday confirmed the Frenchman's switch.