Kane suffered the problem during Tottenham's 1-0 defeat to Manchester United at Wembley on Sunday as he received treatment at the end of the game and walked off extremely gingerly.
The England captain was injured after being caught in the middle of Phil Jones and Victor Lindelof.
He has suffered an ankle problem and it is no surprise that Pochettino is worried having lost Kane to similar injuries in each of the last two seasons.
Midfielder Moussa Sissoko was also injured on a damaging afternoon for Spurs, whose title ambitions all-but died.
"I think I am worried because we will see what happens with Harry Kane," Pochettino said.
"I think Moussa is only a small thing but we will see, we need to assess Harry Kane.
"At the end I think he suffered a big tackle and twisted his ankle and now we need to assess him over the next few days, hoping it is not a big issue."
Any lengthy absence for Kane would leave Spurs short of attacking options ahead of an important part of the season, with Son Heung-min going away on international duty, Lucas Moura still injured himself and Fernando Llorente and Vincent Janssen expected to leave the club this month.
Kane did not emerge through the mixed zone after full-time as he was selected for a post-match doping test, so it was unclear how heavily he was walking or whether he had a foot brace on or needed crutches.
Sissoko's first-half injury was another blow for Spurs as they conceded less than two minutes after he hobbled off.
It looked like a hamstring problem, which the Frenchman tried to play through, but it was in fact a groin injury.
"No it was groin, a small thing in his groin. Let's hope it is not a big issue too," Pochettino added.
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