The striker was shown a yellow card by referee Glenn Nyberg for striking Arsenal defender Gabriel in the throat with his elbow.
Hackett told the Telegraph: "Harry Kane can count himself a lucky boy. His swinging elbow to the face of Arsenal defender Gabriel ... was dangerous, reckless and with excessive force.
"Kane knew exactly what he was doing, as you can tell from his glance back at Gabriel to see where his opponent was positioned. I'm sorry, but as soon as you take your eyes off the ball and play the man, you are asking for trouble.
"This was a prime example of that where Kane used his elbow as a weapon, and the swinging motion combined with the look back at Gabriel moments before the contact leaves the Bayern Munich striker no defence.
It qualifies as a violent action and had he committed the offence in the Premier League, I am sure he would have been sent off. It is a nailed-on red card for me.
"Kane can consider himself extremely lucky to have only received a yellow card that leaves him available for the second leg with everything still to play for. It could come to be a crucial and potentially decisive moment in the quarter-final tie."