Matthew Connors was detained for four hours and questioned by immigration officers before being sent back to New York early on Friday morning, the South China Morning Post newspaper said in the report.
The former head of Massachusetts College of Art and Design's photography department said it was the third time he had travelled to Hong Kong since the anti-government protests erupted in June 2019, and believed the decision to deny him entry was taken before he even arrived.
"Immigration officers told me repeatedly that based on the interview they conducted with me I did not 'meet the immigration requirements'," the newspaper quoted Connors as saying.
"I asked them to be more specific several times, but they would not provide more information.
"The interview was also strangely informal. The immigration officers seemed indifferent to most of my answers, taking lacklustre notes, though they asked the most follow up questions about the book I published about the Egyptian Revolution," he added.
Connors, who won the International Center of Photography's Infinity Award in 2016 for his book, 'Fire in Cairo', visited Hong Kong in August and September 2019 to cover the unrest as an independent journalist.
He was detained by police on his first visit, but not charged.
The Hong Kong Immigration Department has declined to comment on the case, said the South China Morning Post.
"In handling each immigration case, the Immigration Department will, having regard to the circumstances pertaining to each individual case, decide whether the entry will be allowed or refused in accordance with the laws of Hong Kong and prevailing immigration policies," it said in a statement.
( With inputs from IANS )