Spurs have only lost once in the Premier League this term, away to Manchester United on the opening day of the season, and sit fifth in the standings after 12 matches.
Tottenham finished fifth and made the Europa League quarter-finals in Dembele's first season at the club, but he believes the class of 2015 are even better.
"This is best team I've played in since I've been at Tottenham," Dembele told Sky Sports.
"[Mauricio] Pochettino is very much aware of the way we play, the way we press and our mentality. He is trying to change the culture of the club and that was needed.
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"Of course we've had a taste that we can reach the Champions League but we have to be focused game by game to achieve that.
"We are not thinking too much ahead. We have a good feeling at the moment so we are capable of doing anything, we just need to stay strong and focused all the time instead of thinking about where we can end up."
Tottenham go head-to-head with London rivals West Ham on Sunday, bidding to consolidate fifth spot.
"We are very strong as a team and there is a good atmosphere in the group," Dembele added.
"We're playing very much as a team, something we haven't done much in the past.
"It is not one or two players playing well, the team is playing well and that allows for someone if they have an off day - it's a good thing."