"I've seen Straight Outta Compton - my wife and I saw it when it first opened, the first weekend, and it just rocked our world. It was incredible. I was very surprised to see that omission."
However Spielberg isn't convinced Oscar voters were driven by race when they made their all-white picks for the top acting and film awards.
"I don't believe that there is inherent or dormant racism because of the amount of white Academy members," he added.
"I'm also not 100 per cent sure that taking votes away from Academy members who have paid their dues and maybe are retired now and have done great service - maybe they've not won a nomination, which would have given them immunity to the new rules, but they have served proudly and this is their industry too - to strip their votes? I'm not 100 per cent behind that."
Academy bosses voted last month to strip many inactive members of their votes in reaction to the nominations controversy.
Spielberg is a fan of the idea to increase the numbers of African-American and women voters.
"I do think that what the Academy is doing, in a pro-active way, to open up the membership to diversity, I think that's very, very important," the director said.
"But it's not just the Academy, and I think we have to stop pointing fingers and blaming the Academy. It's people that hire, it's people at the main gate of studios and independents. It's the stories that are being told ... and we all have to be more pro-active in getting out there and just seeking talent."
- WENN