Novak Djokovi

VIDEO: Tennis star Djokovic visits UN refugee camp in Serbia

He spent time with the youngsters at a UNICEF-supported "child-friendly" space in Belgrade on Tuesday

Djokovic, who is a Goodwill Ambassador for UNICEF, said he was hurt personally at seeing children who "don't know where they are going, where they are heading, what tomorrow brings."

Since the beginning of the year, 129,947 people have been registered in Serbia as asylum applicants, UNICEF said in a news release.