The outburst from the Italy international came after Samp goalkeeper Emil Eudero saved his shot in Sunday's clash at the Dacia Arena, which the Zebrette won 1-0.
Mandragora was deemed to have shouted "Porca Madonna, Vaffanculo, Dio Cane", expressions which are akin to the English "damn it" or "for God's sake" but which have a stronger literal meaning.
Indeed, "Porca Madonna" would translate directly into "Pig Virgin Mary" while "Dio Cane" would become "Dog God".
The remarks initially went unnoticed by officials during the match, but Serie A's governing body later took the incident to review and suspended the 21-year-old.
"After acquiring and examining the relevant television images, the player, while cursing without referring to anybody around him, was nevertheless clearly seen by the television images to make blasphemous remarks, visibly identifiable from reading his lips without any margin for reasonable doubt," a disciplinary report from the Lega Serie A said.
There is a strict ban on taking God's name in vain in Italy and, since 2010, the country's football association has disciplined players and coaches heard doing so.