"I am sure this visit will be a fundamental part of our ability to overcome together the challenge of fighting terrorism, atrocity and evil that we all have to confront together," Renzi added, referring specifically to Islamic State militants, who oppose Iran and the West in equal measure.
Rouhani had originally been due to visit Europe in November but canceled the trip after an Islamic State attack on Paris, which killed 130 people.
"We have always been in the front line against terrorism. We have to continue (cooperating with Italy) to secure a genuine peace in Afghanistan, Syria, Lebanon, Libya," the Iranian president said, speaking through a translator.
Many Western nations have accused Iran of funding various militant groups, and despite a landmark nuclear deal between world powers and Tehran last year, the United States is keeping some of its financial sanctions in place because of the alleged links and human rights abuses.
