Barnes will be reevaluated next week after tests this weekend revealed no broken bones, according to the team.
The undefeated Warriors (18-0), who are off to the best start in NBA history, begin a seven-game road trip Monday against the Utah Jazz. Barnes also will miss Wednesday's game against the Charlotte Hornets and Saturday's game against the Toronto Raptors.
Barnes suffered the injury in the third quarter of Friday's victory over the Phoenix Suns. Warriors interim coach Luke Walton told reporters Saturday that the team would be cautious with Barnes' return and said they want to avoid "lingering injuries."
"We'll have him take his time," Walton said, according to the San Jose Mercury News.
Barnes, 23, is Golden State's third-leading scorer and is averaging 13.4 points and 5.0 rebounds in 17 games this season.