"No country is without risk, we have raised the level of alert to re-sensitize those units charged with protecting sensitive places," Interior Minister Angelino Alfano said on Friday.
"Today has seen three attacks with dozens of dead carried out in three different places around the world, linked by one thing: violence and terror," he said.
Italy had raised its alert level to the third-highest in January, after the jihadist attacks in Paris, AFP reported.
Alfano did not specify to what grade he had increased the level on Friday, after a massacre at a beach resort across the Mediterranean in Tunisia and a grisly attack in southeast France.
At least 37 people were killed and 36 wounded when a gunman opened fire on holidaymakers on a beach in the Tunisian resort town of Sousse.
Meanwhile in France, a businessman was found decapitated at a gas factory near Lyon, while further afield in Kuwait, a suicide bombing at a mosque claimed by Islamic State in Iraq and the Levant (ISIL) terrorists killed at least 25.
Alfano shot down claims that would-be terrorists may be entering Italy via migrant boats crossing the Mediterranean from Libya, hidden among the over 60,000 people who have washed up on the country's shores so far this year.
"We will win the terror challenge only if we do not allow ourselves to be conditioned by fear," he said, adding that "there is no proof that there has been a rise in crime as a consequence of the rise in immigration".