The daughter of Katie Holmes and Tom Cruise recently broke her arm and she was spotted on Wednesday with a white plaster cast on which someone has scrawled the playful message.
According to Us Magazine, the note said: "No butt smacking with this!"
It was reported last week that Suri, seven, had been hurt, but a representative for Katie - whose divorce from Tom was finalized last year - insisted she was doing well after her accident.
They previously confirmed: "Suri did break her arm, but she is okay."
The 'Don't Be Afraid of the Dark' actress is living with her daughter in New York, but it was recently claimed Tom is looking for a London home so Suri can be nearby when he's working in the UK.
A source had said: "Tom is happy because he thinks putting down roots in London will allow him to take Suri for longer stretches of time.
"He is just trying to do something nice for Suri. She has been grounded in the United States for a long time and Tom wants to make sure she gets to experience life fully and know other cultures.
"He doesn't want her to grow up to be a narrow minded person who's afraid to use her passport."