"Discussions will continue," Indianapolis Motor Speedway spokesman Ron Green said, according to The Associated Press.
"We believe a return of formula one to our calendar, especially during our centennial era, the period between 2009-2011, would be appropriate. But it must be on terms reasonable to all the groups."
Green said of the draft 2009 calendar published by the FIA on Wednesday: "We want to stress it's just a provisional schedule.
"We continue to be interested in the return of the United States grand prix."
The US GP was held at the famous Indianapolis venue between 2000 and 2007.