The ex-Arsenal midfielder does not think that the striker played as well as he could have done in his side's 2-1 victory over Uruguay.
While Merson conceeded that the Spurs man did take his chances well when he got them, he has a bigger role in the team that just scoring goals.
"They need Harry Kane to hold the ball up, get involved and bring other players into the game. I don't think he did that.
"That's being a little bit too critical and I'm thinking ahead to the knock-out stages."
The former England international also believes that as the tournament goes on, we will see the best of Dele Alli, who is a doubt for the game against Panama because of a thigh problem.
"Dele Alli needs to be playing in games where the other teams are going to have a go at us and there's grass on the other side.
"He's very good without the ball and makes good runs, but there's got to be space.
"In the first two games there will be 10 behind the ball, but against Belgium and in the knock-out stages I think Dele Alli will be a better player."
Merson believes that England will face no problems in the next match against Panama with or without Alli, predicting a 3-0 win for the Three Lions.