The Eagles (3-1) jumped out to a 10-1 lead over the Dolphins, who failed to score a field goal in the first eight minutes of the game.
Jacksonville (0-3), coming off a heartbreaking 71-62 loss to No. 22 Georgetown, cut the lead to seven midway through the second half but could get no closer. American shot 15 of 21 from the floor in the second half and made 5 of 7 shots from behind the arc.
Ben Smith led Jacksonville with 18 points. Despite shooting 3 of 12 from the floor, he made 12 of 14 shots from the free throw line. Aric Brooks added 11 points off the bench for Jacksonville.