The star explained that someone had created a page supposedly belonging to her 14-year-old daughter Emily, and had even included photographs and information from her daughter's real Facebook profile.
Marsh tweeted: "Help get this weirdo off Facebook! Could be dangerous."
She added: "They are stealing pics from her actual Facebook. I'm gonna give it to the police."
Marsh's daughter Emily and 16-year-old son David are from her previous relationship with Dave Cunliffe.
The Coronation Street actress is due to marry boyfriend Jamie Lomas next month.
The pair are rumoured to have sold their wedding rights to a magazine for £500,000.
The couple were previously said to have put their wedding on hold following reports that Lomas had cheated.