RCMP Cpl. Lucy Shorey says Stephen Harper was not in the Langevin Building at the time.
The building was evacuated as a precaution and a joint RCMP-Ottawa police team that deals with potentially hazardous materials was called to the scene.
Shorey declined to provide details about the person of interest or the package.
The historic Langevin Building, which dates to 1883, sits immediately across the street from Parliament Hill.
The incident comes as the government prepares for today's speech from the throne, which sets out its parliamentary agenda for the forthcoming House of Commons session.