Horford scored 15 points for the Hawks, who suffered two defeats in a row for the first time this season.
"We had some careless turnovers, and I think that impacted the game in the third quarter," Horford told reporters. "After that, you have to give them credit. They made shots. A lot of them were tough shots, but they made them.
"They made a run, and we really couldn't recover after that."
The Hawks face the Houston Rockets on Wednesday night.