Police are investigating and have appealed for information about the incident, which happened at 1:15pm on Friday at the Overgate Shopping Centre in Dundee.
The assault is alleged to have occurred in the upper mall of the centre near Millie's Cookies.
An man, described as Asian, was witnessed carrying the child during the incident.
The child was reportedly distressed, but unhurt.
Police Scotland said in a statement the man was about 6ft, between 30 and 40 years old and wearing a fleece burgundy body warmer and dark jeans.
Anyone with information is asked to call police on 101.