It means that Kane, a £1.25m arrival from Liverpool in mid-October, will be sidelined for the Easter programme against Reading and Luton Town and the home game with Middlesbrough on April 10.
But if all well, he could potentially be back in the fray for the trip to Coventry City on April 18.
Meanwhile, Ismael has confirmed that international duo Daryl Dike and Michal Helik can through the international break unscathed and will be available for the Good Friday home game with Reading.
Ismael said: “Dee-Kay (Dike) is well and has been back since Monday. The last few days for him was only recovery and this will be the last training before the game.
“Michal comes back today (Thursday) without issues. He texted me yesterday evening after the game and said everything is fine, so we only have an issue with Herbie Kane, who will miss out again.
“Herbie has a knee injury and needs two weeks more to come back.
“The two others who are out are Liam Kitching and Ben Williams. Otherwise, all the players are refreshed and motivated for the last effort.”
Meanwhile, Ismael is confident that Polish international Helik will not have any issues with fatigue after featuring for Poland in their World Cup qualifier against England at Wembley on Wednesday evening - and potentially playing a second game in less than 48 hours.
On Helik, who made his international debut for the Poles in their game with Hungary last week, Ismael continued: “The good thing is when we saw the schedule in March for the guys was that it was exactly the same situation.
“For example, we played Chelsea on a Thursday and then Brentford on a Sunday. But now it is less than 48 hours between the game (for Michal).
“But I think that Michal is ready and I felt in the texts that he was really motivated and delighted to come back and join the team and that shows the spirit.
“Maybe next week, we can give him more days free to recover from the last international period.
“It was a big moment for him and for sure, it will help him to bring that experience to have a new confidence with us. We will have benefits from this situation and he will have big benefits.”