The growing interest in the sport has prompted talk of a London franchise, and Goodell on Friday hinted that further expansion in the country could be on the cards.
Speaking in his annual pre-Super Bowl press conference in New Orleans, Goodell said: "We are announcing today [Friday] that our two games on London (in 2013) are already sold out. It is a sign that the game is growing globally.
"I think the message is clear. There are passionate fans who love the NFL in the UK. There is another step we now need to look forward to.
"What is the next step? Do we move to three games? Are there other ways to grow the game in the UK? This is a market where we need to be more active and to grow our game."
Six successful games have taken place at Wembley since 2007, with two further games scheduled for later this year. The Minnesota Vikings take on the Pittsburgh Steelers on Sunday, September 29 and the Jacksonville Jaguars face the San Francisco 49ers on Sunday, October 27.