Israeli State TV said U.S. intelligence services have warned Rome that it may face an attack following the shootings in Paris.
But this has been rejected by press spokesman Revd Federico Lombardi: "We are adopting an attitude of caution and attention, but there is no sign of any specific risks.
"The Vatican and the pope may be targets, as are naturally all institutions in Italy and the rest of Europe. But it is not opportune to feed a state of particular alarm, because at the moment it is neither justified or well-founded".
Islamic State has previously published a magazine featuring an image of the Vatican with an IS flag flying.
The Italian Interior Minister said although there had been no direct threat the Holy See was on high alert and that security had been increased.
