The Parisiens suffered a 1-0 home defeat to their fellow title contenders, Lille, in a game that they saw Neymar being sent off on his return from injury.
Ahead of their Wednesday Champions League clash with Bayern, Paris Saint-Germain fell three points away from the top of the Ligue 1 table as a 20th-minute goal from Jonathan David sealed Les Dogues the victory.
"It's going to be difficult," Pochettino told PSG TV.
"We knew very well that it was going to be tough until the end and of course we need to keep going and think of all competitions. We've got the Champions League coming up so we'll focus on that."
PSG saw themselves held back from creating opportunities as a well-organized Lille was able to maintain their 1-0 lead.
"They created fewer chances than us but they were more clinical in front of goal," Pochettino said.
"I think we deserved more at least a point or even three. In the end we lost and of course we're very disappointed with the result. We didn't create enough. We created more than them but not enough and maybe we showed a lack of aggression in the final third. We were thinking that with the dominance we would score but in the end the time ran out we didn't score and we lost the game."