The Belgium international midfielder started the FA Cup fifth-round tie against Palace at White Hart Lane on Sunday afternoon.
However, the 28-year-old did not finish the game in North London and was taken off during the half-time interval.
Pochettino has explained to BBC Sport why Dembele was substituted at the break, claiming that the former Fulham player had picked up an injury during the first half.
The Tottenham head coach has also addressed the issue of tiredness in the squad, stating that his players are not suffering from fatigue.
"There was no tiredness,” Pochettino told BBC Sport. “If we analysed the game we played better but you need to score. It's hard to explain. Mousa Dembele had a smaller groin problem. That's why we changed him at half-time.”
Tottenham fans will hope that Dembele’s groin problem is not a serious one, as he is one of the key players in the team.
The 28-year-old midfielder has scored three goals and created 18 chances in 21 Premier League appearances so far this season.
The Belgian has a pass accuracy of 89% and a shot accuracy of 67%, and has won 20 headers, 55 dribbles and 63 tackles.