Roberts also said shortstop Corey Seager will remain in Arizona through Friday to work on his swing after recovering from a strained oblique.
Kazmir, 33, will go on the disabled list with an unspecified left hip injury. He averaged just 84 mph and topped out at 87 mph against the Texas Rangers on Sunday in his first start in three weeks.
Kazmir missed most of the last two months of the 2016 season with back and neck issues. He finished the season with a 10-6 record and 4.56 ERA in 26 starts.
"As far as the potential disabled list, it's looking like he'll start the season on the DL," Roberts said. "I told him we've got to figure this out. It's not his arm, but we've got to get to the bottom of it. It's something with the hip. We just can't understand why there's just no velocity. Don't know if it's a strength thing or what."
Seager, 33, will miss the first two games of the Freeway Series in Anaheim against the Los Angeles Angels on Thursday and Friday to get more at-bats in minor league games.
Seager will rejoin the team on Saturday for the final Freeway Series game at Dodger Stadium.
Seager, who hit .308 with 26 home runs and 72 RBIs in 157 games last season, is expected to be ready to play on Opening Day next Monday against the San Diego Padres.
"Corey's healthy and it's just ramping up the at-bats," Roberts told reporters from spring training in Phoenix. "We want him to feel comfortable in the batter's box. Tomorrow he'll be off, Wednesday he'll log four to five or six (innings). I would expect him to miss the two games in Anaheim. For me, realistically, he'll be back for the last game at Dodger Stadium."