Former military diver Jean-Luc Kister on Sunday broke his 30-year silence and said sorry for his part in the bombing on 10 July 1985, which killed Portuguese photographer Fernando Pereira and destroyed Greenpeace's converted trawler.
The Rainbow Warrior was docked in Auckland ahead of a protest against French nuclear testing at Mururoa Atoll, about 1,200 kilometres southeast of Tahiti.
The Greenpeace flagship's captain Pete Willcox told Radio New Zealand he accepted Kister's apology was genuine but said it should not obscure the harsh truth about the attack.
"I accept the apology, I think it was sincere ... I hope that it allows him to sleep better and live his life out.
"But it doesn't change the fact he and his friends - president Mitterrand and everybody that was part of that team, who planned the operation and carried it out, are murderers -- that should be part of the story."
Willcox rejected Kister's suggestion the photographer's death was accidental, saying he did not believe an elite military dive squad with explosives training could bungle an operation so badly.
Two of the agents who took part, Alain Mafart and Dominique Prieur, were arrested in New Zealand shortly after the bombing but spent only a short time in jail under a deal reached with France.
Willcox said most of those responsible, including Kister, had never faced justice for their actions.
"Two people that were part of the team spent a year in jail ... No, I don't think justice was ever done. I think that's a ridiculous notion."
France has officially apologised for the incident, paid compensation and stopped its nuclear testing in 1996.