The 17-year-old striker is understood to have attracted the interest of Liverpool and Manchester United after impressing in the youth setup at Craven Cottage.
Despite attention from elsewhere, Jol wants Dembele to stay in West London and develop his career with the Cottagers.
"Dembele came in two years ago and is still under contract," the Dutchman told the Fulham Chronicle. "He's only 17 now, but he's strong and scores goals every match. I took him up to the Under-21s already.
"The boy loves it here. The only thing we've got to do is, in the next couple of years, try to keep him here."
Fulham continue their battle to avoid relegation from the Premier League on Saturday when they travel to fellow strugglers West Ham United.