The child is rarely seen in public, and the last time Suri was spotted was a brief appearance in her father's arms during her parents' honeymoon, where they were surrounded by eight bodyguards.
During the baby's appearance at the Cruise-Holmes wedding in Italy, the family was protected by at least 200 police officers, as well as members of an Italian security force.
Katie, 28, and Tom, 44, apparently fear their baby could be a prime target for abduction.
"The world was so obsessed with getting its first peek at Suri, I think Tom and Katie might have decided to keep her under wraps to prevent some wacko from trying to abduct her," a source told Star.
Historically, celebrities have faced various threats of abduction, which could prompt the couple's worries. David Letterman's son, Victoria Beckham and Russell Crowe were all the supposed targets of foiled kidnapping plots.