The only person associated with the club who has stated Top 4 as an aspiration is Terry Paine, as quoted in the Echo last week.
All Pochettino has done is batted back a journo's question in a tongue in cheek manner when asked if he shared a player's ambition (Boruc?) to qualify for the champion's league in two years. Much in the same sarcastic way he batted back the "is Luke Shaw leaving?" question with: "nah, I'm gonna raid Chelsea's team instead".
Neither the manager nor chairman have explicitly stated that it is the club's aim to finish in the top 4 next year (which isn't to say they aren't aiming for such an eventuality of course)