Earlier this week, a magazine reported that 29-year-old Disick had popped the question to Kourtney, 33, while on vacation in Paris.
However, Kim said that the reports were unfounded, reported TMZ online.
"She is not. It is not true," Kim said.
Not wanting to put too much of a damper on the situation, Kim did show some optimism towards Kourtney's future.
"One day she will be," she added.
Kourtney has been dating Disick for five years and together they have two children - two-year old Mason and four-months-old Penelope.
