Blues legend Zola has been tipped as a potential successor for interim boss Rafael Benitez at Stamford Bridge next season.
But the former West Ham boss, who spent seven years at Chelsea during his playing days, insists he is committed to Watford for now as he looks to steer them into the Premier League.
Asked if he would like the Chelsea job, the Italian told The Times: "I would like to answer that question but I can't. It would be unfair to other people.
"That club is special for me, but for now I'm committed here."
Zola also defended the amount of loan players Watford have signed this season, with 14 currently on their books, 10 of which have been borrowed from sister club Udinese.
Under Football League rules, clubs are only allowed to name five loan players in a matchday squad, but loan deals arranged with foreign teams are recognised as transfers.
The Hornets' loan signings have drawn criticism from some, with Crystal Palace manager Ian Holloway branding the loophole as "ludicrous".
But Zola said: "I paid attention for a little bit, but I stopped because it is nonsense.
"We're not doing anything wrong. We're just playing football, in many cases better than the opposition. That's what matters."