Tahiti, who won gold at the 2011 Games, led throughout the match.
In the first quarter, Tahiti easily scored to lead 21-12 against the weak defense by the home girls.
Tahiti maintained their lead in the second quarter, 35-25.
Aggressive play from PNG's Betty Angula and Louisa Wallace didn't scare the Tahitians as they fought hard to lead the third quarter 42-38.
The final quarter was a close encounter as PNG bounced back to level the score at eight minutes to full time.
But Tahiti managed to get back in the lead in the dying minutes to claim victory.
Fiji will play American Samoa in the gold play off this evening.