Djokovic was seen tossing his racket in frustration as he lost in three sets to Busta over the weekend. Nadal, who was preparing for the Citi Open in Washington, was asked about Djokovic.
"Luckily there weren't any people in the stands and nothing else happened," he told reporters, via The Daily Mail. "He's a point of reference for a lot of children, but these things happen from time to time. He has to try to avoid them."
He added: "It's strange that someone who has had so much success should react that way from time to time but at the end of the day he's very competitive and reacts like that. It's not the best image."
Nadal, Djokovic and Roger Federer each have 20 grand slam titles and will be looking to gain an advantage at the upcoming U.S. Open. He last won the U.S. Open in 2019. He has four U.S. Open titles under his belt.
Djokovic was looking for the Golden Slam last week but was bounced from gold medal contention by Germany’s Alexander Zverev.