Simović was a member of the Serbia under-18 team that finished 10th at the 2016 FIBA Europe Under-18 Championship in Samsun, Turkey. Over seven tournament games, he averaged 3.8 points, 4.2 rebounds, and 0.6 assists per game. Simović was a member of the Serbian under-20 team that finished 15th at the 2019 FIBA U20 European Championship in Tel Aviv, Israel. Over seven tournament games, he averaged 9.9 points, 7.1 rebounds, and 1.7 assists per game.