"As far as we know, the relevations by the Guardian are not true," said foreign ministry under-secretary Mario Giro.
Britain's Guardian newspaper reported on Wednesday that Islamic State fighters had kidnapped four foreigners near the northern city of Aleppo: two Italian women, a Dane and a Japanese national.
It said they had all been taken to Raqqa, the IS stronghold in northern Syria.
Italy had announced on August 6 that Vanessa Marzullo, 21, and Greta Ramelli, 20, of the aid group Horryaty had been abducted by gunmen in a village near Aleppo.
"The government is doing everything to secure their release and we hope it will happen soon."
Another Italian, the Jesuit priest Paolo Dall'Oglio, has been missing in Syria since July last year.