The actor said he once thought of cutting his hair but was stopped from the show's makers, reported People magazine.
"It has its own contract, definitely," Harington said on Live With Kelly and Michael.
"I never thought I'd say that about my own hair... I'm not allowed to cut it, and I didn't realise this until recently. I wanted to cut it - I've had long hair for ages - and and they were like, 'No, no, no. That won't be happening'."
"They don't like doing that. It's very funny when you get into these things, and people get very obsessed by little things... There's all of these ridiculous conversations that go back and forth between agents and managers and HBO: 'Can we have four inches off or can we have an inch off? What can we do with this? How curly should it be? It's silly," the actor said.