ROME—Italian police said on Sunday they had arrested 12 people, including top officials of the far-right party Forza Nuova, following clashes in Rome against a government drive to make the COVID-19 “Green Pass” mandatory for all workers. Thousands of people took to the streets of the Italian capital on Saturday, with many chanting “freedom, freedom” as some attempted to break past police in riot gear deployed to guard access to Prime Minister Mario Draghi’s office. A separate group smashed into the headquarters of Italy’s main CGIL trade union. Draghi introduced the pass—a digital or paper certificate confirming its holder has received at least one vaccine dose, has tested negative, or recently recovered from the virus—in the summer. It was initially required to enter many cultural and leisure venues and its scope has gradually been widened. Last month, the government made it compulsory for all workers. Under the green pass system …