Utley had an MRI on Saturday.
"It's been bothering him enough and bothering me enough, frankly, to go ahead and precautionary do that," general manager Ruben Amaro Jr. said of the MRI. "Rather than really pushing him early, we're going to kind of take it easy on him so there are residual effects throughout the year."
Utley has been taking regular batting practice. His knee becomes painful in explosive baseball movements, such as running and fielding.
"It's a little tendinitis in the knee," Utley said. "I've had it in the past. It comes and goes. It's not going [away] as fast as I wish it would, but I think at this point it's better to be safe than sorry. I'd rather miss a few games here than in the season."
The Phillies do not have a definitive timetable for when they expect Utley to play in a spring training game.
"There's no reason for us to push him now and make it a problem later," Amaro said. "When he's comfortable playing in games, we'll play him in games and go from there."
Utley, who turned 32 in December, played in 115 games last season, his fewest since becoming an everyday player. Although he said the team "hasn't even explored" the option of surgery at this point, he is no stranger to going under the knife.
Utley has had three surgeries in the last four years: his right wrist in 2007, on his right hip after the 2008 season and on his right thumb last July. Before last season, Utley had been averaging 152 games per season from 2006 to 2009.