Paunović was a member of the Serbian under-16 team that competed at the 2016 FIBA Europe Under-16 Championship in Poland. Over seven tournament games, he averaged 14.6 points, 4.0 rebounds and 2.9 assists per game. Paunović was a member of the Serbian under-18 team that won the gold medal at the 2018 FIBA Europe Under-18 Championship in Latvia. Over seven tournament games, he averaged 16.7 points, 4.1 rebounds and 3.4 assists per game. Paunović was a member of the Serbian under-19 team that finished 7th at the 2019 FIBA Under-19 Basketball World Cup in Heraklion, Greece. Over seven tournament games, he averaged 7.3 points, 4.6 rebounds and 4.4 assists per game.