The National Union of Journalists (NUJ) has written to Sinn Fein leader Gerry Adams to express deep concern at his remarks about a newspaper editor being held at gunpoint.
NUJ General Secretary Seamus Dooley said Mr Adams's comments, made at a fundraiser in New York, were both "ill-judged" and "inappropriate".
The veiled threat against the editor of the Irish Independent has been widely condemned by several senior ministers and international journalism groups.
Justice Minister Frances Fitzgerald described the remarks as "abhorrent", while Tanaiste Joan Burton said they represented a threat to the country's free press.
The NUJ yesterday said the remarks have been deemed both "sinister and intimidating" by members of the media.
"I found the comment ill-judged and inappropriate in the context of the daily threats of violence against journalists across the globe, the number of journalists killed annually and the climate of fear in which so many colleagues work," he said.
Mr Dooley also said he was concerned at the "disturbing" tone and content of comments made by senior party officials on social media.
"Robust exchanges are part and parcel of political discourse but some of the comments made have not only been personalised but offensive," he said.
Health Minister Leo Varadkar also said Mr Adams's comments were inappropriate.
"I imagine it was intended as some form of joke but I think it is a bit inappropriate for someone who was involved in a murder campaign in the past to start joking about killing people or holding them at gunpoint," he said.