A policeman was punched in the back of the head by a woman as bottles were hurled at officers on a main road.
Officers were targeted on Stanley Road, in Kirkdale, shortly after 4pm on Wednesday as they worked to tackle anti-social behaviour in the area.
While taking part in the local operation, a bottle was thrown at police and the officer was attacked.
A short time later two people were arrested for a range of offences and taken into custody.
Merseyside Police confirmed that a 28-year-old woman, from Kirkdale, was arrested on suspicion of assault on an emergency worker.
A 30-year-old man was also arrested on suspicion of obstructing an officer in the execution of duty.
The officer that was involved was not seriously injured and was able to continuing working.
In a statement, the force said: "Merseyside Police can confirm two people have been arrested following an incident in Stanley Road at around 4pm this afternoon, Wednesday, 26 August.
"Officers from the local policing targeted team were in the area as part of a pre-planned operation to tackle nuisance and anti-social behaviour, when a bottle was thrown in the direction of the officers and officer was punched to the back of the head.
"A 28-year-old woman from Kirkdale, was arrested on suspicion of assault of an emergency worker and a 30-year-old man also from Kirkdale was arrested on suspicion of obstructing an officer in the execution of duty.
"Both have been taken to a police station where they will be questioned.
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"The officer was able to carry on with his duties."
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