Although both teams had already qualified for the quarter-finals, there was plenty to play for with top spot in Group A on the line.
Tahiti, inspired by an excitable crowd and the now familiar pre-match Polynesian Haka, played with their usual speed and verve and Teva Zaveroni hit the post early.
Merida then gave Spain a handy lead with a classy but opportunistic strike from long range before the first break.
Pajon took advantage of a momentary lapse in the Tahiti defence to volley home unchallenged as Spain moved four clear before the halfway point of the contest.
Patrick Tepa pulled one back just before the end of the second period with the goal producing massive excitement from the crowd despite the remaining task at hand.
Raimana Li Fung Kuee drew Tahiti closer with a superb dead-ball strike from halfway, but despite their best efforts the home side saw their nine-match unbeaten run come to an end.
The result leaves Spain in a quarter-final showdown with El Salvador.