A NASA statement said only that SpaceX data from a recent launch attempt of another Falcon 9 rocket showed "off-nominal behavior" in the generators, and the delay would allow the company to complete tests and review more data.
"We're now targeting [not earlier than] early-to-mid November for launch of NASA's SpaceX Crew-1 mission to the Space Station," NASA's Associate Administrator Kathy Leuders posted Saturday on Twitter.
"The extra time will allow SpaceX to resolve an unexpected observation during a recent non-NASA launch attempt."
Launch of the six-month mission, SpaceX Crew-1, is to be the first regular trip to the International Space Station as part of NASA's Commercial Crew Program, which allows NASA to contract for launch services from private companies. The mission would be the first ever of a capsule with four people on board.
SpaceX owns the rocket, but NASA has full knowledge of the company's launch and testing data, Leuders noted.
"The teams are actively working this finding on the engines, and we should be a lot smarter within the coming week," she said in a statement.
The crew for the mission consists of mission commander Michael Hopkins, 51, pilot Victor Glover, 44, and mission specialists Shannon Walker and Soichi Noguchi, both 55. Noguchi is a Japanese astronaut.
The previous crewed SpaceX capsule, which returned to Earth on Aug. 2, carried two astronauts and spent two months in orbit.
The issue with the rocket engine will not delay two other upcoming Falcon 9 launches for the space agency that will carry a satellite and supplies to the space station, NASA said.
The astronaut mission is to lift off from Complex 39A at NASA's Kennedy Space Center in Florida.