Nelson, drafted in the fourth round last year out of Southern Mississippi, started 12 games as a rookie for the Bills. He caught 17 passes for 156 yards.
Nelson can practice and play throughout the remainder of the Bills' preseason. The Bills were already short-handed at tight end after Derek Schouman hurt his knee in Thursday's 34-21 preseason victory over the Indianapolis Colts.
Nelson' suspension begins Sept. 4, eight days before the Bills' first regular-season game against the Miami Dolphins.
Nelson's agent, Joel Segal, declined comment when reached by The Associated Press.
Information from The Associated Press was used in this report.