The commissioner's office issued the penalty Thursday.
Fiers is not appealing, so the penalty starts in Thursday night's game between the AL West-leading Astros and playoff-contending Angels.
On Wednesday, Fiers unleashed a pitch at least 2 feet over Valbuena's head that sailed to the backstop when Valbuena came up for the first time after hitting his 20th home run of the season and then adding an exclamation point with a big bat flip.
"I took it as disrespect,'' Fiers said.
Plate umpire Cory Blaser immediately warned both benches. Houston manager A.J. Hinch would not comment on the pitch.