Unused substitute Cataldi received a red card in the 66th minute of the Rome derby, having grabbed Strootman's collar, prompting the Dutchman to drop to the ground in an exaggerated manner and leading to a confrontation between players and staff on the touchline at Stadio Olimpico.
Footage later showed Strootman had antagonised his opponent by tossing the contents of a water bottle in Cataldi's face after scoring the opener in a 2-0 win. Italian authorities have now taken retrospective action against the 26-year-old.
Cataldi has only been given a one-game suspension, while Strootman, having been found guilty of seriously unsportsmanlike behaviour in the form of provocation and simulation, will miss important Serie A matches against AC Milan and Juventus.
Lazio's Senad Lulic, meanwhile, remains under investigation by the Italian Football Federation after making comments about Roma defender Antonio Rudiger that were construed as racist by many commentators.