Pochettino accused Xavi of doing Manchester City's dirty work and said the former Barca player had "tried to destroy our focus."
Responding in a joking manner over Xavi's comments, Pochettino said the 37-year old, who is now playing in Qatar, “lied and cheated” during a 1-0 victory for Guardiola's Barca over his Espanyol team in 2009.
"He's in a period when he loves to talk, he's in Doha and - listen - he was a Barcelona player, he's my enemy. He tried to destroy our focus to win because he hates me, because he's Barcelona - a player, a fan, you know," said Pochettino.
"I know him [Xavi] very well, I played against him a lot and when I was a manager [at Espanyol]. Yesterday, Thierry [Henry] was here and we remembered the game where he [Xavi] cheated the referee. He fell down, it wasn't a penalty, but [Zlatan] Ibrahimovic scored for Barcelona and they won.
"The marking man was Raul Baena, Xavi fell down and said 'penalty.' They gave a penalty. After, in the video [replay], it was very funny because no one touched him and everyone in the media was saying, 'No, no trust me - it was a penalty.' Come on! It goes from lie to lie to lie.
"I don't know what Xavi said but he is working for Manchester City, maybe? He wants to help Guardiola and [club captain Vincent] Kompany."
Earlier, the Spurs boss refused to give any guarantees over Alli’s future at Spurs. Alli, along with Kyle Walker, Danny Rose and Christian Eriksen have all been linked with moves away from the club this summer.
"I think because we are doing good things, the clubs with a lot of [financial] potential are focused on our players, on our talented players. But it is important, I told you, because my relationship with Daniel Levy is so close - so far! You know the relationship between chairman and manager can change in a moment," he said.
"The good thing is we have the plan to try to improve. And we will deliver it when we finish the season. Like I told you, the players that we want to keep, we will keep.
"Because he [Levy] said to me, 'We don't need money.' If we sell some players it is because we want to sell some players. We will sell players because of the players we want to sign.
"For our fans, it is so clear that all the decisions we take are for the reason to try to improve the team, try to be more competitive next season."