Kalinić was a key player in the Croatia national under-21 team during his youth playing years, also representing his country at the under-17 and -19 level. He first made a name for himself at international level at age 17 during the 2005 UEFA European Under-17 Championship when he finished the campaign as the top scorer with 11 goals. At the under-19 level, he managed another five goals during his side's preliminary round of the same tournament. He also scored a hat-trick against Lithuania in Croatia's 3–0 victory, which secured them a spot in the next elite round of the UEFA European Under-19 Championship in 2006.