Edwin Encarnacion gave the Dominican all the runs they needed in the first inning, and starter Samuel Deduno (1-0) held Puerto Rico at bay for five innings before turning the game over to the bullpen.
Erik Aybar drove in the other Dominican Republic run. Jose Reyes chalked up a double and a triple and scored a run.
Giancarlo Alvarado (0-1) took the loss for Puerto Rico. Alvarado allowed two runs on two hits.
Puerto Rico, which defeated defending champion Japan in the semifinals, put two runners on base with no one out in the seventh inning. Strop came in from the bullpen to take over for Dotel and struck out the next two batters before getting a fly out off the bat of Jesus Feliciano to end the inning.