Despite being only 18, Mendy has significant experience having made 57 appearances in the last two seasons in Ligue 2 and represented France at under-16 to under-18 level.
"It's now up to him to reach an agreement with them. We are okay."
The left-back has also been courted by Lyon, and Louvel did not rule out the Champions League qualifiers returning to hijack the deal.
"We were close to an agreement with Lyon, it has not happened but you never know," he said.
"Right now, the only club we are in agreement with is Sunderland and it is now up to Benjamin Mendy to make his choice."