Teenager Pan powered to Olympic gold on Wednesday in 46.40secs, demolishing his won world best of 46.80 set in February to win by a body length.
Pan had only just squeezed into the semi-finals a day earlier when he clocked 48.40, two seconds slower.
Hawke, an Australian Olympic sprint freestyler himself who went on to mentor Brazil's Cesar Cielo, the first man to break 47 seconds, claimed the world record time was "not humanly possible".
"Listen, I'm just going to be honest. I am angry at that swim, I'm angry for a number of reasons," he said in an Instagram video.
"My friends are the fastest swimmers in history -– from Rowdy Gaines to Alex Popov to Gary Hall Jr, Anthony Irvin, all the way up to King Kyle Chalmers.
"I know these people intimately, I've studied them for 30 years. I've studied this sport. I've studied speed. I understand it. I'm an expert in it, that's what I do, okay," added Hawke, who is now a US citizen.
"That's not real, you don't beat that field -- Kyle Chalmers, David Popovici, Jack Alexy -- you don't beat those guys by one full body length in 100 freestyle. That's not humanly possible, okay."
The win came against the backdrop of a doping controversy that has engulfed the Chinese swim team in the lead up to Paris and led US authorities to accuse anti-doping governing body WADA of a cover-up.
The New York Times in April reported that 23 Chinese swimmers had tested positive for the banned substance trimetazidine (TMZ) at a domestic competition in late 2020 and early 2021 ahead of the Tokyo Olympics.
Pan is not among the 23 swimmers in the report.
Chinese authorities said the positive tests were the result of food contamination -- an explanation accepted by WADA.
China's swimmers have been among the most heavily tested ahead of the Olympics.
"Last year I received 29 tests, and it has never been positive," said Pan after his win, which he called "a perfect performance".
"I was tested after the race and we will see the result."
Australian veteran Chalmers, who won 100m gold in Rio and silver in Tokyo, accepted Pan's performance without question.
When asked by Australian media if he thought the record was clean he replied: "Yeah".
"I do everything I possibly can to win the race, and I trust that everyone's doing the same as I am and staying true to the integrity of sport.
"I trust it, I trust that he's done everything he possibly can to be there and he deserves that gold medal.
"I did everything I possibly could to challenge for that gold medal and be on the top of podium. I'm silver and I'm just as happy with that."
