A petrol bomb was thrown at a mosque in the town of Newtownards to the east of Belfast in the early hours of Saturday morning, in an incident described by police as racially motivated.
The mosque was attacked at around 1 am (0000 GMT), with graffiti sprayed on the front door and walls of the building on Greenwell Street.
Police said the petrol bomb thrown at the property did not ignite.
Chief Inspector Hutchinson said: "This is being treated as a racially motivated hate crime, and I want to send a strong message to those who carried this out, that this type of activity will not be tolerated and any reports of hate crime are taken very seriously.
"I am appealing to anyone with any information or footage that could assist with enquiries to come forward and help to identify those responsible and put them before the courts."
It comes as police said several protests in Belfast city passed off without incident on Friday evening, however, police said they are investigating a number of overnight reports of damage to property and vehicles.
Cars were set alight in Tavanagh Street and Sandhurst Gardens in Belfast and police said both incidents are being treated as racially motivated hate crimes.
The rear door of a restaurant on Ormeau Road was also kicked with racial slurs shouted at the workers inside.
Five people were arrested on Friday, bringing the total number of people arrested to 31.
A 22-year-old man was arrested following Friday's protests in Belfast accused of throwing a bottle at a police vehicle.
He will appear in court on September 6 charged with offences including disorderly behaviour and criminal damage.
A 51-year-old man also arrested following the city centre protest activity has also been charged with disorderly behaviour and will appeared in court on Saturday.
Meanwhile, two 14-year-old boys were arrested in the north-western city of Londonderry following protest activity in Guildhall Square.
The arrests came after a number of petrol bombs were found by police in the vicinity of Spencer Road.
Both appeared before a special sitting of Dungannon Magistrates' Court on Saturday.
A 37-year-old man was arrested in Portrush on suspicion of 'intentionally encouraging riot' in relation to online activity remains in police custody at present.
Temporary Assistant Chief Constable Melanie Jones said: "We continue to investigate all reports made to us in relation to the recent disorder on our streets and we will be making further arrests.
"The outpouring of support from our communities for their Muslim neighbours has been heartening and more accurately reflects the views of most of the citizens of Northern Ireland.
"We will continue to have a significant visible policing operation in place across Northern Ireland over the weekend to ensure our communities are kept safe."
It comes as thousands of people took to the streets of Belfast on Saturday in an anti-racism demonstration.
