Ciriaco put San Diego in front during a two-run seventh with his triple and then added a two-run blast in the eighth for insurance.
Los Angeles climbed into a 2-2 tie in the sixth on a sacrifice fly by Juan Uribe, but the Padres jumped back in the lead one inning later and held on to win for the first time in three games.
Yasmani Grandal began the San Diego seventh with a ground-rule double off Matt Guerrier (3-2) and Ciriaco followed with his triple that gave the Padres the lead.
Logan Forsythe was intentionally walked with one away and Ciriaco was then thrown out at home on a grounder to first by Will Venable. Forsythe moved to second on that play and he came in to score the second run of the inning on Chase Headley's single.
Ciriaco's home run in the ninth came after Grandal had reached on a single.
All of that made a winner out of Nick Vincent (2-0), who worked the top of the seventh. Huston Street appeared in the ninth in a non-save situation and gave up a homer to Mark Ellis.
Los Angeles eventually brought the tying run to the plate, but a double-play grounder got Street out of the inning.