"We're going to shut him down so we don't cause more damage," Roberts said. "Get him ready for next year. ... I know he's very disappointed."
Elbow and back injuries have limited Gonzalez to 71 games this season, his lowest since playing in 43 games in 2004, his rookie season with the Rangers. He's posted a .242/.287/.355 slash line with three homers and 30 RBIs.
"With the way that the season's gone, where I've had a number of setbacks," Gonzalez said, "you don't want to go into the postseason, play a game and come back, have a setback and have to figure if you're down for the day. Just too many question marks there."
Gonzalez being left off the postseason roster opens the door for Andre Ethier to fill the role of left-handed hitter off the bench, something Roberts mentioned in the past. Ethier is batting .267 with three homers since coming off the disabled list on Sept. 1.
Roberts expects Gonzalez, who is signed through 2018, to rest and come back strong next season.
"I know he's going to play next year, and we expect him to have an Adrian Gonzalez type season," Roberts said.
Gonzalez said his strength is fine, but it's a matter of resting his back this offseason. He does not plan on traveling with the Dodgers throughout the postseason. "My plan is to play every day," Gonzalez said of next season. "Be an everyday player again and give it a go to have a really good season like I expected for this year."
• The Dodgers will not pitch lefty Alex Wood or right-hander Yu Darvish vs. Colorado in the season finale on Sunday. Roberts said the Dodgers will have a bullpen game but haven't decided who will start.
Joshua Thornton is a reporter for MLB.com based in Los Angeles. This story was not subject to the approval of Major League Baseball or its clubs.