The rumours began when Keough, 24, was spotted driving back to Pattinson's Los Angeles mansion earlier this year.
But Lisa, 45, who is the daughter of iconic singer Elvis Presley denied such reports, reported Daily express.
Pattinson recently broke up with longtime on and off girlfriend Kristen Stewart.
When asked if her daughter was dating the 'Twilight' star, Lisa said, "I will say who she is not with... And that is a complete lie, and the silliest thing I've ever heard, is that she was with Robert Pattinson, because she and Kristen Stewart are like best friends."