The operation was among the biggest that have been launched against alleged supporters of Gulen since the failed putsch, in which 250 people were killed. Gulen, a former ally of President Tayyip Erdogan, has denied involvement in the coup attempt, Reuters reported.
CNN Turk said the operation was centered on the capital, Ankara, but was spread across 76 provinces. No further details were immediately available.
More than 77,000 people have been jailed pending trial since the coup attempt and widespread arrests are still routine. Authorities have suspended or sacked 150,000 civil servants and military personnel.
Erdogan's critics accuse him of using the failed putsch as a pretext to quash dissent. Turkish authorities say the measures are necessary to combat threats to national security.