San Fran will open the new season at the progressive stadium in the Bay Area, with Oakland also looking to find a suitable home having had to share their currently antiquated stadium with Oakland Athletics.
"Well, we have two pro teams in the Bay Area. Obviously, the stadium issue in Oakland's going to have to be resolved, too," NFL.com quotes Goodell as saying.
"We believe a new stadium is appropriate for the Raiders. They have to make that determination whether they're in a new stadium in Oakland or whether they feel that it's best to join this stadium.
"We're working on that, and that's one of the decisions they'll have to make."
The NFL previously loaned the 49ers around $200m (£117m) to help fund the new Levi's Stadium.