Navid Rezaeifar was the best scorer of Iran with 20 points and 9 rebounds.
Josh Jackson led USA with 20 points and 10 rebounds.
Iran will take on Egypt, who has lost 111-68 to Croatia, on Sunday. the US will meet Croatia.
The 16 teams from across FIBA’s five regions - Africa, Americas, Asia, Europe and Oceania - were divided into four groups of four teams for the Group Phase, played in a standard round-robin format.
The FIBA U-19 World Championship began on June 27 and runs through July 5.