The director, 79, has called on his fellow filmmakers to "tell more original stories", as opposed to making so many reboots, sequels and spin-offs.
In his first-ever appearance at CinemaCon, he said: "If all we make is known, branded IP (Intellectual Property), we're going to run out of gas.
"There is nothing more important than giving the audience visual stories, and they can be in any form, but we need to tell more original stories."
Spielberg also praised Universal Entertainment chief Donna Langley for moving to a 45-day exclusive theatrical window - seven weekends - for its 2027 movie releases.
"Audiences will find what they want to watch, whether the films are big or small, but studios need to help us by greatly expanding the exclusive windows like Donna Langley just did," he said.
"Today I've got to be greedy. Do I hear 60 days? Do I hear 120 days?"
Also at CinemaCon, Spielberg premiered a new trailer for his forthcoming film Disclosure Day, which features Emily Blunt, Josh O'Connor, Colin Firth, Eve Hewson, and Colman Domingo.
The sci-fi movie involves a government plot to cover up the arrival of visitors from another planet, and Spielberg believes it will result in people asking "a lot of questions" about what else could be out there.
"I've been curious ever since I was a little kid with what was happening in the night sky," he said.
"The world became more accepting of the fact that we probably are not alone.
"I believe this movie is going to answer questions and this movie is going to cause a lot of people to ask a lot of questions.
"All you need to get from beginning to end is a seat belt."
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