The head coach told reporters: "We did not compete on a high level tonight. We can't use excuses of injuries or having played last night.
"We faced a real good basketball team tonight, but the disappointment lies in the fact that we didn't compete at a high level. We didn't lay it on the line. We didn't play as hard as we should have.
"I actually thought [Spurs' top scorer Tim Duncan] moved up and down the floor as well as I've seen him move up and down the floor in some time. It just seems like he continues to get better and better, and I have not seen any slippage in his game."
The Bucks' 5-17 record leaves them bottom in the Central Division.