The countdown was proceeding as planned until a guidance computer triggered an abort 10 seconds before the scheduled 7:36 p.m. Eastern liftoff from Florida.
CEO Matt Desch said the next batch of 10 Iridium Next satellites is scheduled for launch June 29.
The company successfully landed the first stage booster after fairing separation of the NRO payload.
The launch will be the first to use a previously flown first stage, in this case a stage that launched a Dragon cargo spacecraft last April.
SpaceX plans to convert a launch pad at Cape Canaveral Air Force Station, Florida, into a landing pad for the reusable rocket boosters it is developing to power its Falcon family of rockets.
Hoping that the third time is the charm, the Planetary Society announced Jan. 26 that it will launch a solar sail experiment in May as a secondary payload on an Atlas 5 rocket.
Space Exploration Technologies Corp. will attempt to land the first stage of its Falcon 9 launch vehicle on a floating platform in the Atlantic Ocean on its next mission.
SpaceX said it would take one to two weeks to re-examine potential failure modes of its Falcon 9 rocket.