The threat was directed at club owner Massimo Ferrero, a businessman and cinema producer who quit as club chairman after being arrested for allegedly fraudulent bankruptcy in 2021, and a member of the board, Antonio Romei.
The message read "your heads will be next".
Sampdoria are currently sitting in 19th place with 11 points from 23 games, nine points shy of the safety zone.
Their subsequent Monday evening game against Lazio ended in a 1-0 defeat.
ANSA