The Garda Representative Association (GRA) said it is "disappointed" Minister for Justice Helen McEntee will not be attending its annual conference in Mayo next week.
Ms McEntee said it would "not be appropriate" for her to be there after the GRA did not invite Garda Commissioner Drew Harris.
Tensions have been high between the association and Mr Harris due to an ongoing dispute over rosters.
GRA president Brendan O'Connor, says he's surprised by Ms McEntee's decision.
"We're disappointed that the minister won't attend because we always seen that the relationship we have with the minister is different with that we have with the Commissioner.
"The issues we have with the commissioner in our portfolio is in relation to pensions and conditions of employment do not really cross over with operational policing. We saw a separation of power which is in place in most democracies."
However, Ms McEntee has denied taking a side in the dispute, saying she cannot undermine the position of the Garda Commissioner.
"The Commissioner is appointed by Government, and it is really important the Commissioner and the representative organisations can engage, can work through any issue.
"He is head of the organisation, and I believe that being at a conference, and being able to work through and resolve and respond to questions members have is the best way."
'Unfortunate'
Sinn Féin’s justice spokesperson Pa Daly said Ms McEntee's decision not to attend the GRA's annual conference is "strange", given her party's focus on crime.
"It’s very unfortunate that it’s come to this," he told RTÉ radio’s Today with Claire Byrne show.
The public did not want to see "the people who are supposed to be in charge falling out or fighting with each other," he added.
"It's clear that the Commissioner not being invited is a sign of the difficulties that have been there for months now. There have also, of course, been contradictions between what the minister has said about not being appraised of the morale of the gardaí and the GRA themselves, saying that morale is in tatters.
"But I think that it's all the more strange that she isn't attending when there has been a huge focus on crime recently as part of the Fine Gael reset or whatever they're calling it."
Mr Daly said it should have been a priority for Ms McEntee to attend the conference, to show support for gardaí.
"It's all about a question of confidence," he said.
"People need to feel safe in their communities, and they need to feel that somebody is in charge and that the people at the top are focused on one issue, and that is keeping communities safe, reducing the fear of crime in communities, and reducing the cause of and tackling crime.
"I think that she should be sitting down, or her officials, should be sitting down with all sides and trying to work on it. It is a serious problem. People don't want to see squabbling there. And, it's just unfortunate that it has come to this," he added.
Additional reporting from Vivienne Clarke
