Kane was not included in Spurs' squad for their Premier League opener against champions Manchester City, with Son Heung-min scoring the winning goal on Sunday.
It is City who wish to sign the England captain – Pep Guardiola eager to bolster his attack by acquiring an out-and-out centre-forward.
Reports last week suggested City would be willing to bid as high as £150million for Kane, who has three years left on his Tottenham contract and has indicated he would like to leave the club.
Nuno stated Kane was not involved due to only returning to training late last week, though the 28-year-old's omission will hardly help ease the speculation.
While Spurs' boss claimed he is planning to have Kane on board for the season, Nuno acknowledged Tottenham must be ready to reinvest in their squad should their talisman be sold.
"The decision [to leave out Harry] was made on Saturday, the day we prepared for the match," Nuno explained to reporters. "We have to make decisions, it's our job.
"Harry is [training] with us, he worked on Sunday morning and he's getting ready to help the team. We don't expect [something to happen before the transfer deadline but] we have to be ready to act if necessary because until the 31st anything can happen in football.
"We have our squad, we have our Spurs players.
"We have to commit them but we have to know that 31st of August is sometimes not in your hands. All the managers in the Premier League have the same feeling that I have – trying to finish the window and settle down."
Spurs have been linked with a move for Lautaro Martinez, with a fee in the region of £65m (€76.5m) having reportedly been agreed with Inter, though that move is one which would almost certainly depend on Kane leaving.
Without Kane, Spurs impressed in the 1-0 victory over City – their first competitive match under former Wolves boss Nuno.
They registered only 34.4 per cent possession, but had only one less effort on target (three, compared to City's four) and kept the champions at arm's length after a blistering start from Guardiola's team.
Son's strike 10 minutes into the second half settled the contest – the South Korea star has now scored seven times against City in all competitions for Spurs, with only Jamie Vardy (nine) having done so on more occasions.
With or without Kane, Nuno wants to foster a fierce team bond. It is perhaps for this reason that Tanguy Ndombele – Spurs' record signing – and Serge Aurier were also left out.
"That was the idea – going beyond your limits," Nuno said.
"The boys went beyond with their fight and discipline. The way they committed themselves was very good. That's what we have to do every day of our lives.
"I'm very happy with all the team. We're trying to create a unit, everybody has to be engaged, everybody has to be committed.
"Of course, when the players play, they got the recognition of everybody but there’s lots more [happening] behind the scenes. Their commitment.
"We're in a process and we have to keep working hard."
The defeat means City have lost their last three competitive games 1-0, the first time they have lost three successive matches without scoring since 2007, while Guardiola has suffered more away defeats at Spurs (five) than against any other team.