US Open champion Medvedev made the dig soon after telling the noisy Rod Laver Arena crowd with some irritation during his post-match on-court interview on Thursday that they needed to show some respect for his questioner, Jim Courier.
The Russian was unhappy that he felt he had been booed by some of the crowd between his first and second serves en route to his wildly exciting 7-6 (7-1) 6-4 4-6 6-2 victory.
"It's a little bit disappointing," he told Eurosport soon after the match.
"A few moments on my serve, where he managed to make some good returns, and then break point on second serve, and people are cheering like you've made a double-fault.
"That's just disappointing. It's not everybody who's doing it - but those who are doing it probably have a low IQ."
Earlier, Medvedev had tried to tell double Australian Open champ Courier on court about those perceived boos, only for the American to try to play peacemaker by telling him fans were actually just indulging in the irritating new Cristiano Ronaldo goal celebration cry of "Siuuu!"
When they continued the din, an annoyed Medvedev retorted: "Sorry, I can't hear you. Show some respect for Jim Courier. Thank you, guys. Let him speak please.
"If you respect somebody, at least respect Jim Courier."
Later, Medvedev, who's now being tipped by Kyrgios to win the event after his brilliant performance, added in his press conference: "It's not easy to play against the crowd.
"I feel like these matches are not easy to play, but they stay as fun matches afterwards, because in the end, we gave the crowd a big show - probably Nick more, because, well, he's a big entertainer."
The Russian demonstrated with his icy resolve amid all the familiar mad pyrotechnics of the Kyrgios game that he's now himself matured from hot-head into mature grand slam champion. A few years ago, he felt, he might not have beaten the impressive Kyrgios.
Back at the 2019 US Open, Medvedev became the man that the Flushing Meadows crowd loved to hate as he offered them a bird's eye view of his raised middle finger and told them they were just fuelling him with energy.
For his third round match against Dutchman Botic van de Zandschulp on Saturday, it should be intriguing to see how the crowd react to him.
Kyrgios, who could orchestrate a storm in a monastery library, reckoned he had tried to get the umpire to curb the crowd noise between serves but added: "I thought the atmosphere was awesome. That's what sport is.
"You've got the most entertaining player playing in his home slam on Rod Laver. You'd expect the crowd to be like that.
"I can understand it's a gentleman's game but it's about time people embraced some sort of different energy in this sport, otherwise it will die out. It's just that simple."