Five members of the group were reportedly detained by the police.
The activists said in their statement that "the desperation caused by the increasingly alarming statistics of a climate collapse that has already begun" prompted them to commit this act of vandalism.
President of the Senate Ignazio La Russa expressed outrage at the eco-activists' actions and announced that he had convened a meeting of the governing council of the upper house of the Italian parliament on Tuesday to discuss the incident.