Protestors have threatened to block trains with their bodies.
Italy has said there will be a zero tolerance policy against demonstrators who block trains to oppose a Green Pass requirement.
Passengers are only be allowed to use certain public transport if they show a Green Pass, which proves recent vaccination, a negative COVID test in the past 48 hours or recovery from the disease in the last six months.
The rule, announced some weeks ago, applies to domestic flights, train travel between regions and sea travel. Some ferries are exempt, such as those serving many tiny islands which have no other connections to the mainland, and those used by commuters between Sicily and the southern tip of the mainland in Calabria.
Local buses, trams and metros are exempt from the rule, which was announced by Premier Mario Draghi's government when daily caseloads started steadily rising as the delta variant of the virus became prevalent in Italy.
Italy's Green Pass is already being used for those wanted to dine indoors, go to gyms or attend crowded venues like concerts.
On the eve of the new transport rules, Interior Minister Luciana Lamorgese vowed zero-tolerance against any rail track protests or other violence.
Several recent protests against the Green Pass requirement, including in Rome and Milan, turned violent, with police having to rescue a state TV journalist after a protester started yanking her by her hair, and a newspaper reporter was punched repeatedly in the face. Ministers and doctors have received threats.
Lamorgese voiced “the strictest condemnation of the attacks launched with unacceptable tones on social networks against members of the government, politicians, doctors and journalists over the ‘green pass’ and containment measures against the spread of COVID-19."
Police are investigating the incidents.
“No illegal acts will be permitted in protest initiatives at train stations” billed by organisers for Wednesday, Lamorgese said.
Militants of an extreme-right group, New Force, as well as some members of extreme-left organizations have participated in the rallies.
So far, some 70% of Italy's residents 12 years or older have been fully vaccinated. But experts have voiced concern that many people in the 50-69 age group haven't received vaccines nor signed up for them.