Seager was not listed as a starter for Saturday's game against theColorado Rockies, though Roberts said he could be available as a pinch hitter.
The 23-year-old suffered the injury in the second inning of Friday's 6-1 win over the Rockies. He left the game, and Roberts said that an MRI revealed a Grade 1 strain in his hamstring.
"It would be a huge void. When you're playing a premium defensive position and you lose your shortstop and arguably your best hitter, it's a big blow," Roberts said, according to MLB.com. "We talked about the short view, the long view ... to put him in harm's way to potentially have him miss more than he needs to with a Grade 1 would be irresponsible."
Roberts added that keeping Seager out of the lineup will hopefully prevent him from going on the disabled list.
Seager leads the Dodgers in runs scored (56), hits (79), doubles (19) and walks (45). He is hitting .298 with 12 home runs and 39 RBIs on the season.