The actor told Metro that it was not true that he wanted her signature for his children.
"No, it was for me," Neeson said. "She is so cute.
"Sadly, I didn't get to work with her much directly on set but in my first scene I am making a speech to some 500 cadets on a battleship and Rihanna is in there.
"We had a holding area on the ship, a sort of green room, and she was in there with her little posse."
Of why he joined the project, he added: "[Director] Pete Berg is an old friend and when I heard the words admiral of the fleet, Hawaii, Pearl Harbour and 'We need you for one week', I thought, 'Great'. I think it makes a cracking good film."
Neeson admitted to being surprised by his latter-day career as an action star, explaining: "Just look at the success of Taken, for example.
"I thought it was going to be a straight-to-video release. That is actually one of the reasons I did it, to be honest.
"I felt like spending three months in Paris, I'd get to do all this physical stuff that no-one would think of me for, and that the film would go straight to video.
"Then it became this big success. I was a tiny bit embarrassed by it, a tiny bit, but then people started sending me action scripts."