Gonzalez has recently suffered symptoms of a lower back injury.
He was originally placed on the 15-day disabled list on May 21. Following a lengthy absence, Gonzalez appeared ready to play again.
But soreness returned while he was playing with a Kansas City farm team in Arizona last weekend.
Gonzalez was examined by a back specialist on Wednesday and the tests revealed a disc problem. He is batting .276 this year with five home runs and 17 RBI.