The device was discovered on Foreglen Road on Wednesday morning following a telephone call to a local hospital.
The road has reopened after a security alert in the area. The device was taken away for forensic examination.
Det Insp Bob Blemmings said: "We appreciate that the alert caused traffic disruption and are grateful for the patience and support shown by the community and commuters."
The PSNI have found a "viable" pipe bomb in Dungiven, County Londonderry.