The woodland playground in Rathfarnham Castle Park was in the process of being revamped.
Work began on the project in March after South Dublin County Council invested €50,000 in new play equipment.
However, on Friday night some of the new playground material stored on-site was set alight, resulting in €2,000 euro in damage.
Local Fine Gael Councillor David McManus is appalled by what he describes as the actions of thugs.
"It's worrying that this is how some people choose to react when local authorities choose to invest in facilities for local families.
I am appealing to local residents - if you saw anything suspicious last Friday night around Rathfarnham Castle Park, please contact Rathfarnham Garda Station on 01 666 6082".