"This match is the most important one since I've been here and it represents the next step," said Spalletti, who guided three-time winners Inter back to the elite European competition this season for the first time since 2011-2012.
"Since I've been here, we've got the points and put in the performances that we needed. Now, we're here to play for a spot in the last 16 on the final day of the group stage.
"We're all aware of the importance of this game. We've dreamed of playing games like this."
Inter will finish second and qualify for the knockout rounds if they pick up more points than Tottenham manage away to group winners Barcelona.
But Spalletti's side lost 1-0 to Tottenham last time out and are coming off Friday's 1-0 defeat by Juventus in Serie A which left them 14 points behind the champions in third.
"The team is fine," insisted former Roma and Zenit Saint Petersburg coach Spalletti on Monday.
"We've played really strong teams like Tottenham Hotspur and Juventus of late and we've played on an equal footing.
"If, at the time of the draw, we were told we'd be playing for qualification against PSV and Tottenham had to face Barcelona, what would we have said? We've seen that the group's very tough.
"It's still open to any outcome."
Uruguayan midfielder Matias Vecino is still sidelined with Belgian Radja Nainggolan also an injury doubt.
The Inter coach defended captain Mauro Icardi who was criticised for his trip to Madrid on Sunday to watch the Copa Libertadores final.
"I don't have any issue with it, lots of other players from different teams were there too, it certainly wasn't strange for him to be there."
Meanwhile, the Dutch club, who won their only European title back in 1988 and are now coached by former AC Milan midfielder Mark van Bommel, are playing for pride.
"Against Inter it's a derby for me because I played at Milan," said the 41-year-old Van Bommel.
"For Inter it will be an important game. We don't have anything to aim for but we must find the motivation within ourselves."
Midfielder Pablo Rosario added: "It's the last chance we have to play in the Champions League. We struggled to get here, we'll try to prove something."