The 29-year-old started just three Premier League games in 2018 following his return from a lengthy layoff due to a hamstring injury.
Spurs boss Mauricio Pochettino always maintained that Alderweireld was being overlooked because of form issues rather than his alleged reluctance to sign a new contract.
The centre-back, however, went to the World Cup with Belgium and started all but one game as the Red Devils finished third in Russia.
When asked by Belgian publication Het Nieuwsblad about his future, Alderweireld said: "I really do not know anything yet. In my head I just go to Tottenham. We will see.
"I was very focused on [the World Cup]. I wanted to prove something again. Show that the period before the tournament in which I did not play – for whatever reason – was unjustified.
"I wanted to show that I am still the same Toby as in November."
Manchester United have reportedly expressed an interest in snapping up Alderweireld.