The family moved into to five-star Hotel Hassler Roma, located at the top of the Spanish Steps and was overrun with fans and photographers, Us magazine reported.
"He's been my idol since I was a teenager. I can't miss this opportunity. Let me see him. Let me at least take a photo," said a 30-year-old Italian woman standing outside, the Italian news agency ANSA said.
Cruise, 44, and Holmes, 27, are set to be married in Italy Nov. 18, with both of their wedding outfits being designed by Giorgio Armani.
The New York Daily News reported last week that the celebrity couple was already "Velcro'd to each other" at the Conde Nast Black Ball benefit on November 9.