The explosion occurred outside the historic Pizzeria Sorbillo, in the heart of the southern Italian city, five years after the venue was torched.
No injuries were reported, but the restaurant’s entrance on Via dei Tribunali was damaged, forcing the eatery to shut its doors on Wednesday.
The explosion comes seven years after the restaurant went up in flames.
The fire was suspected to have been at the hands of the local mafia as punishment for refusing to pay protection money.
“What saddens me most is that they set a bomb in a place that’s a symbol of this city’s rebirth: I’ve been working for years to put the old town back in the spotlight, with tourists, with local and foreign customers, and all of a sudden they force me to close like this,” said pizzeria owner Gino Sorbillo.
“I’m afraid it’s a warning to other businesses, that they targeted me to say: ‘If we did it to Sorbillo, we can do it to anyone’.”
Local police are examining footage from surveillance cameras in the quest to identify the culprit.
Meanwhile, Sorbillo said his restaurant would reopen “within a few days”.
Sorbillo owns other venues in Naples, Milan and New York, and is internationally praised for his mouth-watering pizzas.
