Deputy Prosecutor-General Vladimir Kolesnikov said a moratorium on foreign adoptions would contravene both Russian and international law.
He complained, however, that wealthy adoptive families from abroad have left adoption costs prohibitively high for Russian families.
Kolesnikov said adoptions cost anywhere between $15,000 and $80,000.
Many Russians have called for a ban on foreign adoptions following the deaths of more than a dozen Russian children at the hands of their adoptive families.
But child welfare activists say a ban would leave thousands of orphans with no hope of a better life.
Russia has 800,000 orphaned children. Some 17,000 orphans were adopted last year, more than half of them by foreigners.