Norway's National Security Authority rejected the application from Apple for permission to fly over the city and take images because the 3-D mapping would include military buildings, the local Aftenposten newspaper reported.
Although 2-D maps of Oslo are available in Apple maps, officials said they had concerns about detailed 3-D views of government buildings.
"We do not want [images] to be shot with such a high degree of precision that it could be used to identify areas that require special shielding," Oyvind Mandt of the National Security Authority told the Aftenposten.
Security measures were tightened by the Norwegian authorities following the 2011 bombing of an Oslo government building that killed eight and injured more than 200.
The U.S. embassy in Oslo has stepped in to support Apple and Oslo's mayor, who reportedly believes 3-D mapping could be a boon for tourism in the capital, also asked the National Security Authority to reconsider.