Matthew and Cindy Hirsch told prosecutors they were in a small supermarket in Garda when they spotted the wine bottles, one of which featured a manipulated image of Hitler posing with the late Pope John Paul II, Adnkronos International reported Thursday.
"I was shocked," Cindy Hirsh said. "It is not just an affront to Jews, despite my husband and I being Jewish. It is an affront to humanity as a whole."
The shopkeeper told the Corriere della Sera newspaper the bottles were a part of history that must remain at the store as a reminder of what happened "to the sons and daughters of those who had carried out these actions."
Prosecutors said they are looking into the matter.
"At the moment the only presumable crime applicable to such an episode is that of apologizing for fascism," prosecutor Mario Giulio Schinaia said.