Mayberry finished 3-for-4, including a go-ahead, two-run double in the fourth inning.
Kevin Frandsen and Domonic Brown each belted a solo homer for the Phillies, who took the opener of a two-game series.
Pettibone (3-0) remained undefeated in his fifth major league start, holding the Indians to two runs on four hits over 6 2/3 innings. He walked two and struck out three.
Tribe starter Scott Kazmir (2-2) was touched for four runs on six hits over five full frames.
Michael Brantley drove in both Cleveland runs.