The "killer clown" craze has continued to spread across the UK with one force dealing with 14 reports in 24 hours.
Officers have been called to a string of incidents where pranksters or criminals dressed as clowns try to scare innocent bystanders.
Chief Superintendent Andy Boyd, of Thames Valley Police - whose force received the 14 calls - warned that the trend, which started in the United States, is a waste of police resources.
He said: "While we do not want to be accused of stopping people enjoying themselves we would also ask those same people to think of the impact of their behaviour on others and themselves.
"Their actions can cause fear and anxiety to other people, this could be perceived to be intimidating and threatening which could lead to public order offences, arrest and a criminal record.
"In addition, their behaviour is causing multiple reports to our call takers and is tying up police resources which could impact on calls to other incidents.
"While we realise that reports of this kind are not restricted to the Thames Valley area, the issues of intimidation, potential arrest and waste of public resources are the same across the country and we would urge people to refrain from such activity."
In Norwich a 30-year-old man was arrested on suspicion of public order offences after allegedly dressing as a clown and jumping out on a woman in a park, screaming and then chasing her.
The victim was walking through Eaton Park in the city at around 8.24pm on Sunday when she was targeted in the creepy prank.
Superintendent Lynne Cross from Norfolk police said: "Whilst this craze may seem harmless, it is actually quite frightening to those who experience it.
"It will not be tolerated and anyone caught with the intention of causing alarm, harassment or distress will be dealt with robustly.
"I would like to reassure members of the public that we are increasing patrols in the area and that my teams have been briefed about this subject."
A string of other forces across Britain have dealt with reports in recent days of people dressed as clowns acting suspiciously and frightening members of the public.
A masked man carrying a knife left a group of children aged 11 and 12 "upset and distressed" when he jumped out on them on their way to the Hermitage Academy in Chester-le-Street, County Durham, at 8.40am on Friday.
A separate report saw two 12-year-old boys, one wearing a clown mask and another a V for Vendetta mask, go to Howletch Lane Primary School in Peterlee to try to scare children in the playground.
In Suffolk, a boy "younger than a teenager" was chased by "several people dressed as clowns" in Beatty Road, Sudbury, at 8pm on Thursday, Suffolk Police said.
Tom Jackson, 18, a first-year student at Leeds Beckett University, said he was "very scared" when he saw a man dressed as a clown near an underpass in Leeds at 4.30am on Friday.
A man dressed as a clown "wearing a hockey mask and a blood-stained poncho" was captured on camera in Ashton-under-Lyne, Greater Manchester, on Thursday.
Police in South Wales, Gloucestershire, Bedfordshire, Essex and Northumbria have also dealt with a string of incidents.
In Sussex, police warned pranksters they could face arrest as they urged people not to dress up as clowns and frighten strangers with a weapon.
Sussex Police said they received "numerous" calls over the weekend from people feeling intimated by the new trend sweeping the country.
Last week a cyclist riding in Eastbourne, East Sussex, reported seeing a person dressed as a clown jump out from a bush holding a suspected offensive weapon.
The man did not speak to him and made no attempt to harm him but the victim was left shaken by the incident, a police spokesman said.
Inspector Simon Starns, of Sussex Police, said: "We are aware this is a trend that has come over from America as Halloween is approaching.
"However, while it is not an offence to dress up as a clown and prank your mates, we don't advise people to do this to strangers in the current climate of heightened security and it is an offence to carry an offensive weapon or an item which could be perceived to be a weapon.
"We will respond if someone feels threatened and the culprit could end up being arrested and then they won't find it so funny."