The Carabinieri said that members of the Last Generation group -- all Italians -- glued themselves to a protective glass in front of the famous 15th-century painting, Primavera or Spring on Friday.
Italian environmental activists glued their hands on Friday to the glass protecting Sandro Botticelli's masterpiece in the Uffizi Galleries in Florence, police said.
The museum said thanks to the glass -- installed as a precaution several years ago -- the painting, Primavera or Spring, was unharmed.
Paired with the Florentine artist's other masterpiece, Birth of Venus, the two iconic canvases dating from the late 15th century are among the museum's most popular artworks. The painting is large, standing at about two metres tall and more than three metres wide.
The Carabinieri said two young women and a man -- all Italians -- bought entrance tickets and staged the protest in the Uffizi's room dedicated to the painter.
The activists sat on the floor and displayed a banner reading "Last Generation No Gas No Coal," police said.
The Corriere della Sera newspaper quoted the activists as saying in a statement, "Today, is it possible to see a beautiful Spring like this?"
The three were taken to a police station in Florence. Italian media said the activists were issued official orders to stay out of the tourist-popular city for three years, using a strategy in Italy similar to that often applied to violent football fans.