Garza has not pitched since July 21 at St. Louis, when he suffered a cramp in his right triceps. An MRI revealed no major damage, although there was slight fluid buildup around the muscle.
The Cubs were targeting a return to the rotation Tuesday for Garza against the San Diego Padres, but Sveum said Garza felt stiff after two weekend side sessions.
"Nothing major, but he's not going to be able to go Tuesday," Sveum said. "He threw two sides, and he was just kind of stiff (Sunday) so we're just going to back him off and send him home to see the doctor and just be a little more precautionary."
Sveum doesn't believe another MRI is necessary for Garza.
"I doubt it if he will get an MRI," Sveum said. "He just had one and it was very clean so just kind of to look at him as much as anything."
Sveum said a decision on a Tuesday starter will be made Monday. But one option, Casey Coleman, is off the table. Coleman started Sunday for Triple-A Iowa and pitched six scoreless innings.