Gardaí are investigating WhatsApp messages which were sent among members of the force about two female officers.
They were described at a meeting of the Policing Authority earlier as "false, insensitive and inaccurate."
The case has been referred to the Garda anti-corruption unit.
According to the Irish Times, In one case, a female senior officer in the Garda was targeted in messages that claimed she had been involved in a drink-driving incident, even though no such crime had taken place.
In other cases, messages claimed named members of the Garda were “scabs” because they had worked overtime on a day when rank and file gardaí decided to withdraw from voluntary overtime as a form of industrial action in a dispute over next Garda rosters.
Deputy Garda Commissioner Anne Marie McMahon described it as offensive.
"Those that are engaging in it, it is just completely unacceptable, and that's why we are so determined on taking such a serious stance in relation to it.
"I suppose there is that whole area of psychological safety, and everybody is entitled to be in a work environment where psychological safety is present."
Ms McMahon told a meeting of the Policing Authority that some of the messages, which were spread in recent weeks, may have been generated and shared on Garda-issue mobile phones.
In a statement made by gardaí, which was sent to all members, it said: "A number of entirely unacceptable communications, particularly on WhatsApp, have come to the attention of the Commissioner. These offensive and inaccurate communications targeting named Garda Personnel contain utterly inappropriate and false material and malicious commentary.
"Such is the Commissioner’s concern in particular for the named individuals so targeted and more generally and pursuant to his responsibilities to all Garda personnel, I am instructed to put all personnel engaged in the creation or ‘sending on’ of such repugnant material on notice to desist from such conduct forthwith.
"Further, I am to advise that the Commissioner has instigated investigative processes to assess the scope of this phenomena and is reserving his position at present with respect what actions, including legal actions he intends to take in response to same.
"Finally, regarding personnel who have experienced this type of unwarranted targeting, the Commissioner asks me to assure you firstly of his unequivocal support, asks that you report it and advises you that organisational support is available, he urges you to seek the available help."
