The San Francisco Chronicle and ESPN have both reported the native of Vaughan, Ont., is unvaccinated.
The city of San Francisco, home of the Warriors, has a vaccine requirement for large indoor events.
The San Francisco Department of Public Health told the Chronicle it would not comment specifically on Wiggins' case unless the NBA grants him a religious exemption.
Wiggins averaged 18.6 points and 4.9 rebounds in 71 games with the Warriors last season before playing for Canada in its failed bid to qualify for the Olympics at a tournament in Victoria.
Selected first overall by the Cleveland Cavaliers in the 2014 NBA Draft, Wiggins has averaged 19.5 points and 4.4 rebounds in 525 career NBA games with the Minnesota Timberwolves and Warriors.