Chief Constable Simon Byrne said recent bomb attacks showed dissident republicans were using a “range of tactics” to attempt to murder police.
Mr Byrne said he was concerned by the increasing pace of dissident republican activity.
It follows the discovery of a mortar bomb near a police station in Strabane, County Tyrone, and a bomb in Londonderry.
Mr Byrne also reiterated a call for the recruitment of more police officers.
Speaking on BBC Radio Ulster’s Good Morning Ulster programme, he said recent attacks were “a departure from what we have seen recently”.
He added that he was concerned by “the engineering behind a range of different devices”.
“There are a range of tactics being deployed by terrorists in different parts of Northern Ireland with one sole purpose, that is to kill or seriously injure one of our staff,” he said,
“I think it is a worrying departure in terms of the determination, the tempo and the motivation of people to clearly kill or seriously injure one of our officers.”
‘Need for more officers’
Mr Byrne said the PSNI needed another 800 officers to take the total size of the force to 7,500.
This was the level envisaged by the Patten Report in 1999 which led to the creation of the PSNI.