Rubio suffered the injury, which included a bone bruise, on Nov. 7 and missed 42 games before returning Feb. 2. After playing 16 of the next 17 games, the ankle proved to be too problematic for Rubio.
"He's just got soreness in that ankle," Saunders told reporters Saturday. "So they want to rest [it], take care of it. There is no use of him playing. We thought, with what we were doing, that he would get relief. And he's not getting relief. So we want to make sure there is nothing else happening in there."
Rubio, who was in the first year of a four-year, $56 million contract extension, played in a career-low 22 games this season. He averaged 10.3 points, 8.8 rebounds and 5.7 assists for the Timberwolves.
Saunders said surgery is not an option at this point.
"We're hoping that rest, the next month, will put him in a situation where he's going to be pretty healthy," Saunders told reporters. "I don't think anyone thought it was going to take the turn that it took. They're trying to do some different things to see if they can get him pain-free."