Sir Jeffrey Donaldson has said the people who made threats against him “now know they are not beyond the reach of the law”.
Police investigating the alleged threats against the DUP leader have said “enquiries were made, no offences were detected”.
The probe was launched after Sir Jeffrey last month revealed he had been threatened due to a “stirring up” of tensions over the party’s talks on Brexit trade rules.
But on Thursday police said the “investigation has now concluded”.
Sir Jeffrey said in a statement that “a decision was made not to press charges”.
It comes just over a year after previous claims made by Sir Jeffrey about intimidation of unionist students appeared to not be substantiated.
He said in October 2022 that “universities should be above partisan politics” before adding that Queen’s Democratic Unionist Association had “recently reported on some very worrying cases of intimidation against unionist students”.
However, the DUP, PSNI or Queen’s University Belfast were unable at the time to provide The Irish News with any information about the alleged incidents.
TUV leader Jim Allister called on the DUP MP to apologise to unionists after the latest investigation into the alleged threats against him detected no criminal offences.
Sir Jeffrey had told the Commons: “I was threatened by those who never put on a uniform, by those who haven’t served our country, and when I checked out one of the people who threatened me, they weren’t even on the register.
“They didn’t vote at the last election.
“They can’t even come out to vote for our future in the union. Yet they’re threatening people like me who are working day and night to find solutions.”
On Thursday, Sir Jeffrey said: “I thank the police for their investigative efforts. A decision was made not to press charges.
“Those who made the threats now know they are not beyond the reach of the law.
“They cannot threaten people in public life and stay anonymous from the police. I want to see more people in public life where issues are debated and discussed through democratic politics alone.
“We must stand against those who would seek to bully with violent threats.
“I wasn’t intimidated out of politics 30 years ago and I won’t be intimidated in 2024.”
A DUP spokesperson said the decision not to press charges was made by the party leader.
But Mr Allister called on Sir Jeffrey to apologise “and withdraw his deliberate slur on those he tried to blacken”.
“Sir Jeffrey Donaldson’s claim in the House of Commons that he had been threatened was couched to try to inflict maximum damage by association with those of us opposing his protocol sell-out,” said the TUV leader.
“He directly linked the alleged threat to such opposition.
“Now that it turns out there was no criminal threat, Sir Jeffrey not just looks, at best, foolish, but needs to man up and withdraw his deliberate slur on those he tried to blacken.”