Tadić was a member of the Serbian U-18 national basketball team that won the gold medal at the 2017 FIBA Europe Under-18 Championship. Over seven tournament games, he averaged 3.1 points, 2.4 rebounds and 1.3 assists per game. He also represented Serbia men's national under-16 team at the 2015 Championship. Over eight games he averaged 4.6 points, 2.0 rebounds and 1.9 assists per game. Tadić was a member of the Serbian under-20 team that finished 15th at the 2019 FIBA U20 European Championship in Tel Aviv, Israel. Over three tournament games, he averaged 0.7 rebounds and 1 assist per game.