A Plaid Cymru AM has been suspended from being a councillor for one month after a tribunal found a comment he made amounted to "bullying behaviour".
The Adjudication Panel for Wales found that Neil McEvoy broke Cardiff council's code of conduct but did not bring the council into disrepute.
Plaid chairman Alun Ffred Jones said the matter was serious and that bullying could not be condoned.
Mr McEvoy called the proceedings a "farce".
He has claimed the complaint was politically motivated.
The tribunal was considering whether Mr McEvoy had made a comment to a council officer in a threatening way following a court hearing at Cardiff Civil Justice Centre in July 2015.
Mr McEvoy, who is a city councillor for the ward of Fairwater, had been assisting a council tenant in an application to suspend a warrant of eviction.
His lawyer had said the South Wales Central AM was "a conscientious councillor".
On Friday, the panel found that the comment by Mr McEvoy - "I can't wait until May 2017 when the restructure of the council happens" - was directed at finance team manager Deborah Carter and was "bullying behaviour".
Chairwoman of the adjudication panel Claire Sharp said Mr McEvoy was "annoyed" following the eviction hearing.
"Effectively you wanted to upset Mrs Carter," she said, and to suggest her job "could be at risk".
The tribunal concluded that Mr McEvoy's' behaviour was not "harassment" but did show a "lack of respect".
Mrs Sharp said that Mr McEvoy had been "evasive" and "unclear" in his evidence, while they found Mrs Carter's evidence to be "reliable".
However, she said the incident was not at the "severe end of the spectrum" and that the panel did not want to prevent him standing at the next council election on 4 May.
Mrs Sharp said there were mitigating factors, including that it was said in the "heat of the moment" and was "one-off", but said there had been no apology from the councillor.
In a final submission to the panel earlier on Friday, the counsel for the Public Services Ombudsman for Wales, Gwydion Hughes, said the council officer had given "a clear consistent account" of events.
But he claimed that during his evidence to the panel on Thursday, Mr McEvoy had been "prone to avoid the question" and "prolix [lengthy] to the point of obfuscation".
He said Mr McEvoy had failed to give a clear account, claiming: "All he ever does is to challenge the account of others."
But the AM's counsel, Jonathan Mendus Edwards, said the comment in question had been made to a constituent, Amanda Williams, who Mr McEvoy had been helping at the hearing.
He said it was "not an intent to threaten" Mrs Carter but "part of his effort to soothe Ms Williams who had just had the worst day of her life".
Mr Edwards said the complaint - which was not instigated by Mrs Carter - was "an attempt to get" Mr McEvoy.
In a tweet, Mr McEvoy expressed his "complete contempt for the farce proceedings which have just taken place".
Labour AM Rhiannon Passmore called for him to be suspended from Plaid Cymru following the ruling.
The first day of Plaid Cymru's conference in Newport has coincided with the final day of the tribunal.
Plaid Cymru's chairman Alun Ffred Jones said: "We will be looking carefully at the judgment and we will be deciding on the course of action next week.
"We expect the highest level of behaviour from all elected representatives and I will be meeting Neil McEvoy next week".