The Redskins announced on Wednesday that Griffin III will start from the bench against the Indianapolis Colts on Sunday, with Colt McCoy to be preferred.
Gruden's decision came in the wake of Sunday's 17-13 loss to the San Francisco 49ers.
Griffin III was just 11-for-19 for 106 with no touchdowns or interceptions as the Redskins (3-8) lost their third consecutive game since the 24-year-old's return from an ankle injury.
Some pundits believe McCoy's promotion may spell the end of Griffin III's career in Washington but Gruden feels the under-fire quarterback needs time to regain his confidence.
"I'm not putting the blame all on Robert," Gruden told reporters during a conference call on Wednesday.
"It seems like that when you make a change like this at the quarterback position.
"Robert has done some good things at quarterback but I just think he needs a little bit more time in this system with the verbiage and the plays to sit back, take a step back and learn, and when he gets back in there he'll be a lot more decisive, hopefully, and ready to roll.
"But right now, I just felt moving forward for Indianapolis that Colt would give us a better chance this week."