Speaking at the Los Angeles press conference for Breaking Dawn - Part 2, Lautner said that Meyer told him not to overthink Jacob's attachment to Renesmee, the daughter of Edward (Robert Pattinson) and Bella Cullen (Kristen Stewart).
"It's a fine line, and I was worried about it," Lautner said of his scenes with Mackenzie Foy. "There was nobody better to ask about it than [Stephenie].
Lautner added: "It's simple - she said it's a lifelong bond between two people and that's it. At this point the girl's like, what, 10 years old? So it's more of a protective thing, like a brother-sister [relationship].
"That's really all it is. I couldn't allow myself to think ahead and go beyond that, so that's kind of the zone I had to stay in."
Breaking Dawn - Part 2, the final film in the Twilight movie saga, will open in cinemas on November 16.
Photo gallery - Breaking Dawn - Part 2 in pictures: