Officers announced they were looking into an interview the comedian gave with the broadcaster RTE in February 2015 when he referred to God as "stupid".
Their probe came after a viewer came forward to say they believed the comments may have broken the Republic of Ireland's Defamation Act 2009.
A source told the Irish Independent: "This man was simply a witness and not an injured party. Gardaí (Irish police) were unable to find a substantial number of outraged people.
"For this reason the investigation has been concluded."
The initial inquiries centred an interview Fry gave on the programme 'The Meaning of Life', when presenter Gay Byrne asked him what he would say to God.
Fry answered: "How dare you create a world in which there is such misery that is not our fault? It's not right. It's utterly, utterly evil.
"Why should I respect a capricious, mean-minded, stupid God who creates a world which is so full of injustice and pain?"
A fine of up to 25,000 euros can be handed to anyone found under Irish law to have published or spoken blasphemous material.