The South Korea international striker left Hamburg this summer but decided to make the move to Bayer Leverkusen instead of Old Trafford for the benefit of his development
The striker left Hamburg to join Bayer Leverkusen but the player's representative claims the Red Devils attempted to bring the forward to the Premier League.
The 21-year-old's agent says Son rejected the move to Old Trafford in order to continue his development as a player with first team football in the Bundesliga.
"Manchester wanted Sonny, they had a strong interest and had contacted HSV. We already talked," his agent told Bild.
"Their interest honoured him, but Leverkusen made the better impression. It's the ideal interim stage for his career right now."
Son scored 20 goals for Hamburg in 73 appearances over three years before leaving for Leverkusen this summer.
He has made four appearances for his new club, scoring once.