DiPietro was injured at 5:40 of the second period after a stretch of Flames pressure during a power play.
After talking to the Islanders' trainer, the netminder left the ice and went straight to the locker room.
DiPietro departed having stopped 13 of 14 shots with the Islanders leading 4-1.
Calgary native Nathan Lawson, who was recalled from Bridgeport of the American Hockey League after the Islanders traded Dwayne Roloson to Tampa Bay on Saturday, replaced DiPietro in goal for New York.
DiPietro had recently missed time with left knee swelling, coming off a short stint on injured reserve to make 37 saves in the Islanders' 2-1 victory over Pittsburgh on Dec. 29.