It might have felt like an earthquake to Sydney coastal residents but it wasn't, scientists say.

Dozens of Sydney coastal residents reported their houses shaking this afternoon but Geoscience Australia said it was not an earthquake.

Residents reported windows shaking about 3.45pm (AEST) in the eastern beach suburbs of Maroubra, Clovelly, Bondi and Tamarama, a Geoscience Australia spokesman said.

"We're pretty happy to say that it wasn't an earthquake," the spokesman said.

"At this stage Geoscience Australia has not recorded any seismic activity. It would certainly have to be very, very small for us not to register it."

Radio talkback callers also reported several houses shaking on Sydney's north shore and northern beaches.