The victim, identified as Nathan Graff, was knifed multiple times by an unknown assailant on Thursday. His injuries are not life-threatening.
The motive for the attack is unclear but police are investigating whether it was a hate crime.
Several Israelis have been stabbed by Palestinians in Israel and the occupied West Bank in recent weeks.
Mr Graff was attacked outside a kosher restaurant. Police are still searching for the assailant.
A statement from Milan's Jewish community said it hoped the attack was an isolated incident.
"We have never had problems in Milan. We don't think this was a personal affair - there is nothing to suggest that," the community's co-president Milo Hasbani told reporters, according to Reuters.
Italy has boosted security at Jewish sites in Milan after an Israeli Jew was stabbed in the city, officials said.