The Warriors levelled the match at 22-22 with 10 minutes remaining when Kaiyah Atai crashed over and Maliepo slotted her only conversion.
The Warriors had momentum in the final minutes, but a costly turnover allowed the Tigers to lead again through Manera before McGregor added a late penalty to seal the eight-point victory.
The Warriors now drop to sixth in the standings with a 4-3 record.
They do sit two points clear of the chasing pack, but face a challenging run home with four games remaining this season, starting next weekend against the unbeaten Sydney Roosters.
Ben Francis is an Auckland-based reporter for the New Zealand Herald who covers breaking sports news.