The iconic film is celebrating its 30th anniversary this year and is one of the highest-grossing films of all time.
But Dee, who played Elliott’s mum Mary, said Spielberg wanted her to bare ALL.
She said: “Steven Spielberg and I butted heads a couple of times.
“I think that’s what it’s about when everyone wants the best and wants to bring the best, they fight for what they think is the best.
“I said: ‘Why? I think that’s wrong.’
“He wanted the cover way down on the bed. I really argued with him about that.
“I was face down in the bed but it’s just little things like that.
“It’s creative decisions that get made in the spur of the moment.”
Dee, 63, also said E.T. was an overnight phenomenon and still a hit to this day.
She said: The only time I remember when it wasn’t a phenomenon was when I was doing it.
“As soon as it came out it’s just been the phenomenon that doesn’t stop.”
For E.T.’s 20th anniversary in 2002, Spielberg re-released the film but changed all the guns to walkie-talkies.
And Dee said she didn’t agree with the change.
She said: “I think it was an expression of our time.
“Do I agree with it? Not particularly but I know Steven felt responsible about what he was putting out for children and I think his intent at that time was to make a statement about violence in the world for kids.”
Dee is starring in new film Fuzz Track City, where she plays a femme fatale who hires a detective to find her son.
She said: “I loved it. It’s actually very close to who I am really. I don’t usually get to play as feisty and as sexy as I think I am.
“I do a lot of mum roles so we had a good time.”