The earlier film saw Bill Campbell playing a stunt man in the 1930s who becomes a superhero when he finds his backpack can help him fly.
Speaking to Film Journal, the director said: "The film didn't do as well at the box office as we all hoped, but it has endured and generated a following. It was great fun and I'd love to re-explore Cliff Secord's world."
He added that he would be "interested" in any projects that feature superheroes as "human" as Steve Rogers.
Johnston also spoke in the same interview about how "not knowing the Captain America character had allowed him to be more "objective" when making the film.
His previous work includes the critically mauled ,">The Wolfman, co-starring Emily Blunt and Benicio del Toro.
Watch the latest trailer for Captain America: The First Avenger below: