The club have also brought in the likes of Roberto Soldado, Etienne Capoue, Paulinho and Nacer Chadli this summer and, although they are expected to lose Gareth Bale to Real Madrid in the coming days, Vertonghen believes that the additions have ensured that they will challenge for a top-four spot again this season.
"I think it sends a message to everybody, to all the top four, that we want to be up there and they have to look at us as well and where we are going to be," Vertonghen told PA.
"Other teams are looking at us. There is a lot of interest in us. There's a lot of competition and the quality of the players is very high here. They have just so much power. I think we have a strong team anyway, whatever happens [with Bale].
"We have bought some very good players and it is always good to have different players who can score."
Spurs have won their opening two games of the season and will look to continue their 100% record when they face Arsenal in the North London derby on Sunday.