At around midday on Sunday, March 6, a four-year-old girl visited the car boot sale at Westfield with her mother and seven-year-old sister.
While looking at the stalls, she became separated from her family and was found very upset a short time later.
The girl told her mother a man had approached her during this time and his behaviour left her distressed.
Police have launched an inquiry into the incident and anyone who can help with the investigation is asked to come forward.
The man is described as being of Easter European appearance, 40-45-years-old, around 5ft 6in tall with a stocky build and dark hair receding in the middle. He was wearing a dark anorak-style waterproof jacket.
Detective Inspector Jim Thomson from Falkirk Police Station said: “At this time, we are continuing to engage with the young girl and her family to determine what exactly has happened and get a clearer picture of how his behaviour has caused the child distress.
“I would ask that anyone who attended the car boot sale and saw anything that can help with this ongoing investigation contacts police immediately.
“In addition, anyone who recognises the description of the man believed to have been involved should also get in touch.”
Information can be passed to police on 101 or Crimestoppers on 0800 555 111.