The former Doctor Who actor stars as Prince Daemon Targaryen in the Game Of Thrones prequel, which is set 300 years before the events of the fantasy drama and is inspired by the George R R Martin book Fire & Blood.
And he revealed to Rolling Stone UK that his character gets plenty of action, joking: "Slightly too much, if you ask me."
He told the mag: "You do find yourself asking, ‘Do we need another sex scene? And they’re like, ‘Yeah, we do'."
He went on: "I guess you have to ask yourself: ‘What are you doing? Are you representing the books, or are you diluting the books to represent the time?’ And I actually think it’s your job to represent the books truthfully and honestly, as they were written.”
The new series follows the story of the powerful Targaryen family and a civil war known as the Dance of the Dragons.
As well as Smith, the cast includes Paddy Considine as Daemon's dad Viserys Targaryen, the king of Westeros, and Emma D’Arcy, who plays Rhaenyra Targaryen, Viserys' daughter by his first wife.
The cast also includes Rhys Ifans as Ser Otto Hightower and Olivia Cooke as his daughter Lady Alicent Hightower.
Smith, 39, has previously said it is very different to Game Of Thrones, which wrapped in 2019.
He told ComicBook.com earlier this year: "I think it's really different to the original series, to be honest with you.
"I mean it has to be. The original series was its own thing and it was, it was so brilliant and, and sort of left a mark in a way that it would be impossible to repeat. So, I don't know.
"The truth is I haven't seen any so it's difficult for me. Essentially it's in the same world, it has to take on a slightly different identity."
House Of The Dragon is due to be unveiled later in August.
Watch: House Of The Dragon trailer