Assistant Chief Constable Mark Hamilton was speaking at a press conference on Tuesday after the discovery of a explosive – triggered by a command wire – in Creggan Heights in the city on Monday.
Police blamed the New IRA dissident republican group for the murder plot.
“This device was there to murder police officers and unfortunately it’s the second of two incidents across the weekend,” said Mr Hamilton.
“There is a concerted effort at the minute to murder police officers and there’s a big effort from our point of view to stop that happening.
“My assessment is that device was there to be used at some point against a police patrol in Creggan.
“We believe the New IRA want to drive policing out of Creggan.
“And they want to deny the people of Creggan the right to phone the police about the most ordinary things – be that domestic violence, sexual abuse, burglary, car crime,” he said.Police searches were launched after a dissident republican mortar bomb was uncovered in Strabane, Co Tyrone, on Saturday.
Fifteen families were evacuated from their homes following the discovery of the viable device.
After bomb disposal experts declared the device safe at 4am on Tuesday morning, the families were allowed return to their homes.
Mr Hamilton said although the device was small in size, it would have had a big impact had it detonated.
“This device was packed with commercial explosives and was small in size but actually the explosion created would have been significant.
“From our perspective it definitely would have killed people standing near it and it definitely would have wounded other people and would have had a significant blast,” he said.
On Tuesday, the PSNI released images of the device discovered in a parked car in the city.
They showed the car where the bomb was found is in close proximity to neighbouring houses on either side.
SDLP leader Colum Eastwood said the people of Derry have “rejected violence”.
“The discovery of this bomb again underlines that violent dissident republicans are ramping up their efforts to break our peace and murder people in our community,” the Foyle MLA said.
“The people of this city and people across this island have rejected those who have tried to divide us with violence, we will reject them again.“Those responsible like to think that they are in an ages old battle with crown forces in Ireland. They are not.
“They have set themselves against the peaceful and democratic wishes of the people of Ireland. Their fight is with us and they will never win.
On Monday night, police were attacked with missiles by members of a crowd of 60-100 people as they carried out searches targeting dissidents.
Around 40 petrol bombs were thrown during the disorder, which was sparked after police announced they were looking for bomb-making equipment in the Creggan Heights area of the city.