Klasnic has joined Premier League side Bolton on a season-long loan deal with a view to a permanent deal.
“Nantes wants to be back in Ligue 1,” he told Ouest France.
“A return is not excluded, my heart wanted to stay. I liked the players, life was good and I had friends.
“But I took this decision to leave and play in a top division and preserve my place with the national squad.
“Bolton is a new story for me.”