The Argentinian's position had been thrown into question following the departure of chairman Nicola Cortese this week, casting further doubt over the futures of star players such as Luke Shaw.
Chelsea have been linked with a move for the teenage left-back for some time, while Manchester United have also reportedly shown interest as they seek a long-term replacement for Patrice Evra.
"I want to make one thing clear: no one is for sale at Southampton, no one," he said.
"No player that I don't want to leave will leave this club."
However, Pochettino's long-term intentions remain unclear, with the 41-year-old adding: "It's only normal that we finish the season and then we'll see next season what happens. That's only normal.
"It's clear that at the end of the season we will assess the situation at the club."
