Prince Albert of Monaco criticised Prince Harry for airing his troubles in public.
The Monaco ruler told the British royal he should have kept his dissatisfaction within the family.
In a rare interview, he said he was bothered by the prince and his wife Meghan Markle's tell-all interview with Oprah Winfrey.
His comments refer to the interview this month in which the Duke and Duchess of Sussex told Winfrey that a member of the family – not Queen Elizabeth II or the Duke of Edinburgh – had made a racist comment about their son Archie.
The duke also said that none of his relatives spoke out in support of Meghan after the racism he said she faced in the media.
As the son of Princess Grace of Monaco, Prince Albert will be all too aware of the struggles for a Hollywood star joining a royal family. Grace Kelly, as she then was, married Prince Rainier in 1956 and was compelled to give up her acting career.
He criticised a 2014 film, Grace of Monaco, starring Nicole Kidman, which focused on Grace's supposed desire to return to her acting roots when offered a part in Marnie by Alfred Hitchcock.
Albert said the film "cannot under any circumstances be classified as a biopic".
Grace died in a car crash in 1982.
Prince Albert described Harry and Meghan's interview with Oprah Winfrey as inappropriate.
Meghan also spoke of being suicidal while in the royal family but claimed she received no help after revealing her suffering.
Speaking to the BBC's Yalda Hakim, Prince Albert said: “I think this type of public display of dissatisfaction, to say the least, these types of conversations should be held within the intimate quarters of the family.
“And it doesn’t really have to be laid out in a public sphere like that. It did bother me a little bit.
“I can understand where they’re coming from in a certain way but I think it wasn’t the appropriate forum to have these kind of discussions.
But Albert, married South African Olympic swimmer Charlene Wittstock in 2011, did reveal some sympathy for Harry.
“It’s very difficult to be in someone’s place,” he said. “I can understand the pressures that they were under.”
Asked whether he would give Harry any advice, he said: “I wish him the best, but it’s a difficult world out there. I hope that he can have the judgment and wisdom to make the right choices.
Albert was speaking during Monaco Ocean Week, an event intended to draw attention to projects, initiatives and activism for the protection of global marine ecosystems.
Harry recently announced two new roles in the US, where he lives with his pregnant wife and their son Archie in Los Angeles.
He announced he is to join the think tank Aspen Institute's new Commission on Information Disorder, as well as taking up the role of chief impact officer at professional coaching and mental health firm, BetterUp.