Roberts said Kershaw is currently shut down from baseball activity while he waits for his back to "calm down."
Kershaw has not pitched since June 26. He seemed to be nearing a return when experience pain following a throwing session over the weekend.
Roberts said the team is "hopeful" Kershaw would be back this season. The lefty leads the Majors in ERA, WHIP and K/BB rate.
"He's disappointed because he knows he can help us," Roberts said. "But his focus is on getting back this year."