"His back's bothering him, so we thought we'd hold him," Giants coach Tom Coughlin said.
Coughlin still expects Pierre-Paul to play Monday night.
Pierre-Paul hasn't missed a regular-season game in his three NFL seasons. But he did sit out the Giants' third preseason game this past August because of back spasms.
Pierre-Paul, who has a team-high 6.5 sacks, was not in the locker room during the media access period on Friday.
The Giants (7-4) enter Monday's contest two games in front of the Redskins in the NFC East.
Second-year linebacker Jacquian Williams likely will not play despite participating in Friday's practice (on a limited basis). Williams has missed the team's past five games with a knee injury.
Williams said he is getting better, but when asked whether he thinks he'll be active Monday, he replied, "I would say no."
On the bright side for the Giants, safety Kenny Phillips practiced Friday after sitting out Thursday's session. Phillips returned to action last week against the Packers after missing six games with a right MCL knee injury, but had to leave the game early after aggravating the injury.
"I'm good. I'm feeling better than I felt. Get better each day," said Phillips, who also said he expects to play Monday night.
Center David Baas (shoulder) also returned to practice Friday, after sitting out Thursday.
Running back Ahmad Bradshaw (foot) and offensive lineman David Diehl (shoulder) were the only other Giants who did not participate at all Friday. Bradshaw has been practicing just once per week to rest his chronically injured foot.
"I'm getting better every week," Bradshaw said.