American lawyer Michael Garcia investigated the bidding processes for the 2018 and 2022 World Cups, filing his findings to Fifa this month.
Garcia wants his report published, and Uefa president Michel Platini is not opposed to it being disclosed.
But Blatter said Fifa is “bound by regulations”.
Any decision to publish now rests with Fifa ethics chief Hans-Joachim Eckert, who is currently considering the report and is expected to announce his ruling next spring.
As well as Garcia, who is the chairman of the investigatory chamber of Fifa’s ethics committee, Fifa vice-presidents Jeffrey Webb, Prince Ali bin Al-Hussein of Jordan and Jim Boyce have also called for the key findings of the report to be made public.
Blatter, meanwhile, played down the controversy over luxury watches being given as a gift to Fifa executive committee officials by Brazil World Cup organisers.