Speaking at a Q&A for his TV series Justified, Leonard said that Freeman and Sandra Bullock are being sought for roles in the adaptation, which will be written by Graham Yost.
"We're trying to get my new book Djibouti [made as a film]. Morgan Freeman likes it a lot. In fact, I even thought of him while I was writing it," Leonard said.
The 85-year-old author noted that Samuel L. Jackson, whose film Jackie Brown is based on his novel Rum Punch, has already turned down a part in the film: "I sent it to him, and he called me up and said, 'I'm not the star of this'. I said, 'Yes, you are. You don't look like you're the star, but you've got all the [good] lines, so you'll be the star'."
Leonard continued: "For the girl, [Morgan] wants Sandra Bullock. And Graham Yost, who's the head writer on Justified, did a Sandra Bullock movie, Speed. He doesn't think that will help him any! But we want him [and] he'll be the screenwriter."
Djibouti, published in 2010, centres on documentary filmmaker Dara Barr as she teams up with a 72-year-old African American seafarer, Xavuer LeBo, to shoot footage of pirates hijacking merchant ships.
Previous Leonard novels adapted for the big screen include Hombre, Get Shorty and Out of Sight.
The second season of Justified airs on FX in the US on Wednesdays at 10pm, and will premiere in the UK on April 20 on 5USA.