Taoiseach Leo Varadkar has defended the decision to commemorate the Royal Irish Constabulary (RIC) in Dublin, saying "all traditions" should be respected.
The government is facing rising opposition over a controversial service for the RIC and the Dublin Metropolitan Police (DMP) planned later this month at Dublin Castle.
A number of mayors have said they will not attend the event, including Waterford mayor John Pratt and mayor for Galway Mike Cubbard.
Mr Pratt said on Tuesday morning that the "appetite does not exist for representation at this event".
Mr Varadkar said that the commemoration is "not a celebration".
"It's about remembering our history, not condoning what happened," he said.
"We will also remember the terrible burning of Cork, Balbriggan, partition and the atrocities of the Civil War.
"We should respect all traditions on our island and be mature enough as a State to acknowledge all aspects of our past."
His comments come after the Dublin City Council voted on Monday night to boycott the commemoration service.
Councillors described the event as "obscene".
The government said the event will commemorate those who served in the RIC and DMP.
Minister for Justice Charlie Flanagan and Garda Commissioner Drew Harris will be among those attending the event.
The Socialist Party tweeted: "Dublin Metropolitan Police engaged in brutal oppression of Dublin working class in interests of the Irish capitalist class in the 1913 lockout.
"The RIC brutally evicted poor tenant farmers and landless labourers in the interests of British landlordism."
Sinn Fein has also called for the event to be cancelled.
Other mayors who confirmed they will not attend the event included Dublin Lord Mayor Paul McAuliffe, Cork mayor John Sheehan and Clare mayor Cathal Crowe.
Mr Cubbard said attending the event would me "hypocritical".
"Attending this event would be hypocritical of me as they directly opposed those whose lives were lost creating the free Ireland we enjoy today.
"History cannot be re-written."
