The Brazilian completed a transfer thought to be worth in the region of £142m last week.
Liverpool managed to hold off the Catalan giants by rejecting three bids in the summer, but they reluctantly allowed Coutinho to leave mid-season after feeling pressure from the player and his camp.
Pochettino, who worked with the playmaker for a period of time at Espanyol, thinks that he knows why the 25-year-old pushed for a move to the La Liga outfit.
"I know Philippe from when we brought him [on loan] from Inter [Milan] to Espanyol [in 2012]. I coached him for six months when he was 17," the Tottenham boss told Onda Cero radio station.
"We know that Barcelona for Brazilians is a special city. Obviously, for Philippe, after five years in Liverpool, where it's very cold and it rains a lot, and when you have your wife and children, it's difficult for a Brazilian to turn down a chance like this one.
"Also, he is joining one of the best clubs in world and the excitement of playing with [Lionel] Messi must also be a factor."
Pochettino has been in England for almost five years having had a spell at Southampton and now Tottenham.