The move will end his string of 226 consecutive starts without a trip to the DL.
Ortiz suffered the injury in his last start June 15 in Chicago against the White Sox. After he experienced pain in a throwing session on Friday, the DL decision was made.
"It's been bothering him for a couple of starts," Manager Bob Melvin said Saturday on the team's Web site.
"I was able to throw my (pitches) in the game without any problem whatsoever," Ortiz said. "After this last start, it turned into something that we had to be concerned about."
For the season, the 31-year-old Ortiz is 4-6 with a 5.88 ERA in 14 starts. Over 78 innings, he has given up 95 hits and 54 runs with 42 walks and 35 strikeouts.