The sites, created in Rome and hosted by internet service providers in the United States, were brought to the attention of the authorities by a Vatican-controlled newspaper over a year ago.
In an operation police hailed as "brilliant", they removed the content from the site and replaced it with the symbol of the special unit involved.
Blasphemy is illegal in Catholic Italy. While bad language has been decriminalised, it still remains an offence to broadcast sacrilegious content.
Police said their censoring of the sites was done so that the "precious freedom of expression" was not used to offend "the dignity of people".
Censoring the net
According to the police, both God and Mary were described in unholy terms, and images of sex scenes appeared next to their names.
A man from Rome may be charged, although it remains unclear what the charges would be.
The Italian authorities are not the first in Europe to try to censor web material posted on foreign internet providers.
In France, the US-based internet service provider Yahoo was ordered to ban the sale of Nazi memorabilia on its pages, following a court case brought by French anti-racism groups.
German legal authorities have also ruled that websites aiming racist propaganda at German audiences could be prosecuted under German law.
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