Off the back of his title successes in Super Formula and SUPER GT last season, Yamamoto was handed a free practice outing in a Honda-powered Toro Rosso at Suzuka during the Japanese Grand Prix weekend in October.
Although Yamamoto is not considered a likely candidate for a future F1 race drive, he said the experience piqued his interest in being able to compete regularly outside of Japan.
Honda is believed to have started considering who might eventually take the place of Takuma Sato in IndyCar when the 2017 Indianapolis 500 winner, who will race for the Rahal Letterman Lanigan team again in 2020, chooses to call time on his career.
But Yamamoto says he feels the risks associated with oval racing are too great and he doesn't wish to follow in Sato's footsteps.
"If I drive in domestic races, Super Formula and SUPER GT, I want to win more titles," Yamamoto told Motorsport.com about his future plans. "But this year I drove a Formula 1 car and I got the feeling that world championship racing is really good.
"So I want to drive in this, against more high-level rivals if I have the chance. If I had the chance I want to drive an F1 car again. I would like to drive an IndyCar as well.
"But at the moment I have no interest in racing in IndyCar. It's a really competitive series, second only to F1, but on the other hand it’s a really dangerous category.
"If it was only road courses and street courses, then I would definitely drive. But ovals... I have a family, and there is too much risk. At the moment I don’t want to race there."
Podium: second place #1 Kunimitsu Honda NSX GT: Jenson Button, Naoki Yamamoto