Smeltzer was recalled from Minnesota's alternate training site in St. Paul on Friday and added to the 28-man roster.
Smeltzer has thrown 16 innings for the Twins this season, making one start and six relief appearances, but he struggled with a 6.75 ERA. With five healthy starters in the rotation and Jake Odorizzi nearing a return, Smeltzer will be used more in middle and long relief than a starter or primary pitcher.