Suspicious devices have been left at churches in Newtownabbey and Ballyclare in recent weeks, while another in Whitehead was targeted by arsonists.
Police said investigations are at an early stage but a sectarian motive has not been ruled out.
They revealed they are putting "considerable resources" into finding out who is behind the crimes and preventing further attacks.
"Dedicated targeted patrols have been implemented throughout the district and crime prevention advice given as appropriate. A number of forensic exhibits have been seized from the respective scenes and are currently under examination," explained a PSNI spokesperson.
Oliver McMullan, Sinn Féin MLA for East Antrim, said tensions are very high in the area.
"People are scared of saying anything at the minute.
"East Antrim seems to be getting the brunt of all of this. All of these chapels that are getting attacked are in east Antrim. There's an orchestrated campaign by unionist paramilitaries to do this," he claimed.
"I will call on Matt Baggott to prove to me that his robust response to all of this is actually working. I will welcome what's happened, that they have said they put on patrols, but it falls far short of a robust challenge."
Two viable pipe bombs were left at the Sacred Heart Church on the Doagh Road in Ballyclare on Friday, forcing the building and nearby homes to be evacuated.
On Saturday, a hoax security alert at St Mary's Star of the Sea in Greencastle forced Mass to be moved to another church at the last minute.
Father Anthony Alexander told UTV, "It's sad - it's very, very sad that people do that sort of thing. I don't know what they're trying to prove."
PUP spokesman Phil Hamilton condemned those carrying out the attacks, and also slammed "irresponsible comments" for stoking tensions.
"The police are saying that they're keeping an open opinion on exactly what's happening and my message to Sinn Féin is quite simple," he said.
"Wait until the facts become available. What's happened is irresponsible comments by Sinn Féin aren't helping community relations.
"Let's deal with the facts, not the fiction.
Police are also investigating the cause of a suspicious fire at Our Lady of Lourdes Church, Whitehead, which broke out in the boiler room in the early hours of 23 December.
Officers said they are working closely with local clergy to find those responsible, however no arrests have yet been made.
"The investigations are at an early stage and all lines of inquiry remain open at this time," the PSNI spokesperson continued.