Renowned coach Harmon suggested the former world No 1’s putting stroke looked too mechanical as he practised at Carnoustie this week.
McIlroy has not won a major in four years with his touch on the greens being regarded as one of his shortcomings of late.
“He looks like a robot out there when I see him practice putting,” said Sky Sports pundit Harmon.
McIlroy was unconcerned by the remarks.
The 2014 Open champion said: “Look, I like Butch [but] definitely I would say I’m on the opposite end of the spectrum than someone that’s mechanical.
“It’s easy to make comments when you don’t know what’s happening.
“I haven’t spoken to Butch in a long time. He doesn’t know what I’m working on in my swing, he doesn’t know what’s in my head.
“So it’s easy to make comments and easy to speculate, but unless you actually know what’s happening I just really don’t take any notice of it.”
McIlroy was pleased enough with his position after the first round despite admitting his performance was a mixed one.
The 29-year-old managed to hit just four out of 15 fairways from the tee and missed some short putts, but he picked up three birdies and dropped just one shot.
He said: “I didn’t see the fairway much, but it’s very playable from not in the fairway. As long as you don’t hit it in the fairway bunkers you’re always going to have a shot at the green. That’s why I tried to stay as aggressive as I possibly could even though I wasn’t hitting the driver maybe as well as I could.
“It wasn’t pretty off the tee, but I got it done and I took advantage of some unfortunate bounces. I would have taken 69 to start the day.”
McIlroy did not shirk from using his driver on the longer holes despite the hard and fast nature of the course making length difficult to control. He intends to keep the same approach today.
McIlroy’s footwear bore the word ‘nasty’ – a play on ‘Car-nasty’, a nickname for the notoriously difficult Carnoustie course.
“All the Nike guys are wearing them,” he said.