The girl was recovered during a raid against an organised crime operation involving alleged cannabis cultivation, money laundering and identity card offences.
She is now being cared for by specialist agencies.
Two men, aged 33 and 35, were arrested in connection with drugs offences as a result of the search.
The raid was the latest strike in what is a wider police operation against organised criminals in Belfast and north Down, and has been running since September 2009.
Police recovered suspected false identification documents and a quantity of cash in the raid but no drugs were found in the house.
