"Releasing the bar manager is unacceptable. It is not only an insult to the victims, it is an insult to the entire Italian people," said Foreign Minister Antonio Tajani, according to Rai.
In addition to sending the ambassador home as a protest, Tajani demands to know who posted the bail for the bar manager.
Swiss President Guy Parmelin says he understands the outrage but will not act and that politicians should not interfere in the legal process.
The man who ran the bar with his wife had been detained since January 9 but was released on Friday.
