The Manchester United manager was said to be interested in signing Dier and spoke to the England global after a game last December.
Pochettino claims that both men have now moved on from the incident and there is no rift between them, however, as Spurs attempt to return to winning ways following their midweek EFL Cup defeat to London rivals West Ham United.
An extract from Pochettino's new book, published this week, detailed how the Argentinian was unimpressed by Mourinho hugging and talking with Eric Dier after last season's match at Old Trafford that United won 1-0.
However, a number of injuries allowed the youngster to make just 16 Premier League appearances during his debut campaign in Manchester, before a horrendous double leg break suffered in a clash with PSV Eindhoven at the beginning of the 2015-16 campaign saw the English worldwide miss the remainder of his second season with the club. I do hope that I can play for him again one day.
"We saw the game they played with Real Madrid and they were not worse than them".
"If he was a central midfield player, yes, because we have only two".
However a double from Andre Ayew restored parity for West Ham before Angelo Ogbonna headed home the victor to end Tottenham's chances of adding to their four League Cup titles, the last of which came in 2008.
Asked whether Shaw still had a future at United, Mourinho said at his pre-match media conference: "Why not?" If you want to speak about his words - I would be very disappointed if his words were different.
"Football is full of examples of lack of character, Luke Shaw was just honest. We'll take the best decision for the team". "I am not ideal, I am human too".
"He has a future here, I think he has, but the situation is not easy because he comes from injury after injury after injury".
"He made me feel that I was the best".