"It's not fun," Cruz said about being on the DL. "I want to play. I run and I feel good. But the safe thing is to rest."
Cruz said he'll continue to hit, run and throw but will do so at a slower pace and work up to when he can return on May 19 in Kansas City.
Manager Ron Washington said the club didn't want to take any chances.
"If he moves the wrong way, we could be looking at more time," Washington said.
Craig Gentry has been recalled from Triple-A Round Rock and should arrive sometime before Saturday night's game. Gentry is hitting .239 with no homers and nine RBIs for Round Rock. He has 11 walks and four stolen bases.
An MRI on Saturday revealed the strain. Cruz has missed the past three games after he was removed from Tuesday's game in Seattle complaining of a tight quad. Cruz first felt it when he tried to leg out an infield hit in the fourth inning and again making a catch in right field in the sixth. He was lifted in the seventh and hasn't played since. He has been able to hit and run, but said Friday that he was running at about 80 percent.
Cruz missed 51 games in 2010 during three different stints on the disabled list, all with hamstring issues. He spent the offseason working on his running style and doing specific exercises to avoid that same injury in 2011.
Before Cruz came out of Tuesday's game, he was mired in a slump. The slugger is hitless in his past 14 at-bats with five strikeouts and is just 2-for-23 with eight strikeouts in his past six games. Since a hot start, Cruz has hit just .161 in his past 16 games to drop to a season-low .219 average.
Richard Durrett covers the Rangers for ESPNDallas.com.