The mural which depicts a young girl firing roses from a slingshot was confirmed by elusive Bristol street artist Banksy on his Instagram and website a day on Valentine's Day.
But, residents in the area woke up just 24 hours later to find explicit graffiti spelling out 'w****r' sprayed in huge pink letters across the artwork.
Kelly Woodruff, who owns the house which acts as the canvas, described the vandalism as "mindless" and says the family have now installed a temporary fence to protect it.
Warning: Image contains language some may find offensive.
Hundreds of tourists are expected to flock to Barton Hill this weekend to catch a glimpse of Banksy's latest piece.
Kelly and her family paid £250 to put up a piece of perspex to protect the art, but that was later torn down.
Several flowers placed over the street sign were also taken.
Kelly says she has now "taken the difficult decision to box the artwork" to prevent further damage, and to restore it.
She added that the family "feels a strong responsibility to ensure the art is available for the enjoyment of the people of Bristol and the general public."
Due to the mindless vandalism to the art work, the family are have taken the very difficult decision to cover the artwork to try to protect the it.
Temporary fencing has been added and CCTV will be installed. The family say they also want to commission bespoke clear viewing boxes.
Banksy is yet to give the mural a name.