Hours after the race, Renault lodged a protest claiming that the floor on the Frenchman's car was illegal.
The French manufacturer's protest focussed on the front of the floor and the radius of its leading corners as specified by Article 3.7.1 d) of the technical regulations.
The FIA had previously issued a technical directive aimed at clearing up any misunderstandings and warned teams that they must be in compliance by this weekend.
However, Haas subsequently admitted that it had been unable to manufacture the new parts in time, which left it open to protest, especially as, according to the stewards, at least one other team had complied with the regulations in time.
While Renault noted the stewards' decision to uphold its request for clarification concerning the legality of the Haas, the French team said it would not offer further comment.
However, taking to social media, Guenther Steiner tweeted: "We do not agree with the Stewards' decision to penalize our race team and we feel strongly that our sixth-place finish in the Italian Grand Prix should stand. We are appealing the Stewards' decision."
The American team has 96 hours to gather the necessary information and officially confirm that it will protest the disqualification.
Grosjean's disqualification means that both Williams finished in point-scoring positions, with Sergey Sirotkin claiming his first ever world championship point.
It also saw Racing Point Force India go seventh in the team standings, having scored 32 points in its first two races, while predecessor Force India scored just 59 points in the first twelve races of the season.