Grey Power says elderly people are increasingly fearful of violent attacks by strangers in their own homes.
Dwayne Lucky Oti, 39, of Manurewa was sentenced in the Manukau District Court on Wednesday to three years and three months in jail for a vicious assault on a woman, 77, in her south Auckland home.
He had earlier been found guilty of burglary and indecent assault.
In the attack in November last year, Oti, pushed his way into the woman's Papatoetoe home wielding a knife, and tied her to her bed with a scarf and bed sheet.
The Crown said it stood by the need for a tough sentence because his offence was very serious, particularly because his victim was vulnerable, home alone and asleep.
Oti's lawyer, William McNicol, said his client has accepted full responsibility, has started an anger management course and is deeply remorseful.
Grey Power President Roy Reid says it wants tough penalties for offenders who target elderly people.
He says many elderly people do not know whether they are safe, and become prisoners in their own homes.
Mr Reid says Grey Power pushes for offenders who attack elderly people to get at least three years in jail.