The Tigers (2-2) had tied it at 70 with 14 seconds left when Trevin Harris hit a 3-pointer from the right wing.
Shaquille Stokes then missed a 3-pointer from the top of the key for the Warriors (2-2). The ball was knocked around at the basket and Jefferson made the putback while being fouled. He then banked in the free throw to make it 73-70.
The Tigers threw the ball away on the ensuing possession, and Zane Johnson hit two free throws for the Warriors with six-tenths of a second remaining.
Johnson finished with 21 points and Joston Thomas added 14 for Hawaii.
Trevor Wiseman scored 10 points and pulled down 10 rebounds for the Warriors while Stokes made 10 assists.
Lorenzo McCloud led Pacific with 23 points.