The Brazilian was replaced at Williams by fellow countryman Bruno Senna for the 2012 season and the 39-year-old will this week test in an IndyCar in Sebring.
However, Barrichello revealed he had promised his wife Silvana that he would not race on any of the oval circuits in the US because of the inherent dangers of the tracks.
"I have no contract with anybody so there's nothing stopping me doing it," Barrichello told the O Estado de S.Paulo newspaper.
"I'm doing it with my mind wide open. If I can get the passion with that car that I have always had when I am driving, then why not? I love racing."
But Barrichello is still hopeful of a return to Formula One.
"The dream of competing in my 20th season is still very much alive. You never know," he insisted.
"Sometimes things change for all sorts of reasons and someone calls up your speed and experience. Kimi Raikkonen and Michael Schumacher came back, so there's no reason I could not as well."