Former Spurs boss Tim Sherwood said the England striker would leave the club if they failed to win a major trophy this season.
Pochettino said: "Harry is one of the best strikers in the world and many people are talking about him.
"Some people are also saying we must win trophies for Harry to stay with us but it's already been made very clear.
"He's one of our best strikers, Harry is our player, he loves Tottenham, he's staying here and he's looking forward to staying here for a long time.
"Tim (Sherwood) has the right to speak about Tottenham and Harry. But that is a question more for Harry and what he's going to do. The answer is Harry has the power and decision to say what he wants to do in the future."
The Argentine coach added: "Harry's one of the best strikers in the world, and that's the confirmation - how people around the world see him.
"It says clearly that people recognise his value and he's one of the best, playing for Tottenham, when we still haven't won trophies."