To make room for Callaspo on the active roster, Oakland optioned first baseman Nate Freiman to Triple-A Sacramento.
Callaspo had been on the DL since July 12 because of a strained right hamstring. He has started more than a dozen games each at first, second and third this season.
The 31-year-old switch-hitter was not in the starting lineup against rookie right-hander Miles Mikolas. Eric Sogard, a left-handed batter, made his 53rd start at second base.