Valverde, out since April 26 with a strained right calf, was available to pitch in Saturday night's game at Arizona. But manager Cecil Cooper said he planned to use Valverde once in a non-save situation before putting him back in the closer spot.
Valverde, who missed 41 games, is 0-1 with a 5.63 ERA and two saves in eight games.
In a corresponding move, the Astros optioned lefty reliever Wesley Wright to Triple-A Round Rock. Wright went 1-1 with a 7.24 ERA in 19 games.