The 2019 finalists this week return to the competition for the first time in two seasons, hosting Marseille in their opening group game.
Spurs will be happy with the make up of Group D, which is completed by Eintracht Frankfurt and Sporting, and Aguero believes with Antonio Conte at the helm Spurs pose a serious threat.
"With [former manager, Mauricio] Pochettino, Tottenham already had a great performance in the Champions League," Aguero told Stake.
"Now with Conte, a coach with a lot of experience, they are managing to be a very solid team. He knows how he wants to play and his counterattack can be lethal.
"[Conte] has added to Kane and Son with Richarlison and two wingers who are very good in [Dejan] Kulusevski and [Ivan] Perisic.
"[Spurs] will be a very difficult rival for any team. They could be a big threat in Europe this year."