The newspaper "Il Gazzettino" (Sunday) reported on the city's decision.
Although the Pope's visit is important for Venice, it is not possible to make arbitrary exceptions for events, of which there are many here, a representative of the city explained.
Due to the high number of tourists, Venice decided in autumn to charge a fee of 5 euros for day tourists.
The measure will initially be tested on 29 weekend days and will become mandatory from 2025.
The test phase will begin on 25 April, three days later Francis will be the first Pope to travel to the lagoon city for the Biennale.
A visit to the Vatican pavilion at the international art exhibition and a meeting with church representatives and the faithful are planned so far.
It is not known whether the Pope will have to pay a daily fee.
Guests aged 14 and over can already register via the platform http://cda.ve.it.
The corresponding QR code must be shown at security checks.
Failure to do so could result in fines of 50 to 300 euros plus an administrative fee of 10 euros.