Fulham were reported to have made a bid for the 23-year-old last month, but his representative Alexander Busac has confirmed there is still plenty of attraction towards the player from Germany and France.
Southampton had earlier agreed a fee for the full-back, after he made clear his desire to leave the Dutch club, but the move has fallen through after supposed demands from a third party for part of the transfer fee.
"At the end, we didn't come to a deal with Southampton and Vitesse," he said.
"We look ahead and happily there is a lot of interest. Hannover and Fulham are very serious.
"Two French clubs have confirmed by mail they are looking to sign Buttner, but haven't made a bid. Within the next days they will contact Vitesse."
Buttner came up through the ranks at Vitesse, making his senior debut in 2008, and has since made over 100 appearances, scoring 10 goals.