The RSA is describing the bashing of a war memorial near Waipukurau as a senseless act of vandalism.
The bronze plaque on the front of the memorial at Hātuma has been struck several times and severely damaged.
RSA spokesman Peter Jackson said it was unbelievable that anyone could have so little respect for the community members who served and gave their lives in the first and second world wars.
He said it would not be possible to fix the plaque by Anzac Day.
Jackson said there had been increased vandalism of war memorials across the country.
He said the RSA supported people's rights to protest, but memorials were not the place to do it.