The team said Tuesday that Beal underwent an MRI after feeling soreness and had the injury diagnosed.
In the spring, a stress injury in a different part of his right leg caused the 6-foot-5, 203-pound Beal to miss the final eight games of his rookie season.
"I'm pretty sure I could probably play, I could probably duke it out," Beal said Tuesday at a shootaround. "But I did that last year and it didn't work out too well. So, I'm just going to play it smart this year and take care of it and just try to get rid of it early.
"Hopefully, it will be gone once and for all."
Beal leads the NBA with 40.2 minutes per game. He is averaging 20.6 points, 4.2 rebounds and 3.5 assists.
"We're taking the right precautions," Wizards coach Randy Wittman said. "Take a couple of weeks off, and hopefully that will do the trick."
The 20-year-old Beal was the No. 3 pick in the 2012 NBA draft.
In addition to Ariza, the Wizards also had forward Chris Singleton active for the first time this season. He missed Washington's first 13 games with a stress fracture to his left foot.