Kane netted on 56 occasions in 2017, including 39 times in the Premier League, as he broke Alan Shearer's record for most goals in the competition in a calendar year.
Ronaldinho told The Mirror that Kane, who has 24 Premier League goals this season, could "walk" into the first-team squads at Barcelona and Real Madrid.
"Harry Kane has been a great player for a while now – but there is no doubt this season he has hit a new level," the Brazilian said.
"He is now at the level where any team in the world would want him. He could walk into any team in Europe. Barcelona, Real Madrid, Manchester City, it doesn't matter how strong the team.
"He is now one of those few players in the world that any team would have to make room for if they had the chance to sign him."
Kane's latest strike gave Spurs a 1-0 win over Crystal Palace last weekend.