A woman in her 30s has been arrested over recent online threats against Tánaiste Simon Harris and his family.
The woman is being held at a garda station in the Dublin region.
After a previous threat, Mr Harris said he would not be "deterred" from doing his job.
In a statement, Mr Harris said: "There can be no hiding place for anyone seeking to threaten, attack or harm people or to incite others to do so.
"Politicians have become a regular target and it is on the brink of being viewed as acceptable or a normal part of the job. It is not acceptable," he said.
"Constant efforts to target us, demean us or dehumanise us should never be accepted, never be normalised and always called out," Mr Harris added.
