The actor is due to star in a fifth Indiana Jones film, which will be released in 2019.
Ford told the BBC: "I've always thought there was an opportunity to do another. But I didn't want to do it without Steven [Spielberg].
"And I didn't want to do it without a really good script. And happily we're working on both.
"Steven is developing a script now that I think we're going to be very happy with," he said of Spielberg, who is directing the film.
Spielberg directed the four previous Indiana Jones films, which were all produced by Star Wars creator George Lucas.
Ford first appeared as Indiana Jones in Raiders of the Lost Ark, released in 1981.
He then starred in three subsequent films, most recently in 2008's Indiana Jones and the Kingdom of the Crystal Skull.
Ford was speaking to the BBC ahead of the DVD release of Star Wars: The Force Awakens, the film in which he reprised his role as Han Solo.
When asked whether Han Solo, who is killed in the film, could return in some form to future movies in the franchise, Ford replied: "Anything is possible in space.
"I wanted Han Solo to sacrifice himself for the good of the other characters to bring some gravitas to the story."
Speaking about his involvement in the film, Ford said: "I was very pleased to have the opportunity to work with the other characters, to work on a script that I had real confidence in, with actors that were a dream to work with, with a director that had a very sure and generous hand, and it was altogether a pleasure."
But Ford said he does not feel an emotional connection to the characters he plays.
"I hope I bring an emotional understanding of the characters and something the audience will recognise," he said.
"I want the audience to experience the character, not to feel that they know him but to be involved in seeing what happens to him."
Star Wars: The Force Awakens became the UK's biggest film of 2015 after just 16 days of release, with takings of Â£94.06m.
Harrison Ford has said he did not want to star in a new Indiana Jones film without director Steven Spielberg.