Kešelj was a member of the Serbian junior national teams, and he played at the 2007 FIBA Under-19 World Championship in Novi Sad and at the 2008 FIBA Europe Under-20 Championship. Kešelj was also a member of the senior Serbian national team at the 2010 FIBA World Championship, where Serbia was defeated by Lithuania, in the game for the bronze medal. He was also capped for the national team of Serbia at the EuroBasket 2011, in Lithuania, where Serbia finished in 8th place.