The Germany winger has been linked with a loan move to Bayer Leverkusen.
"I'm starting to get over my injury problems and feel ready to play. Rafa Benitez, the new coach, told me he wants me to build carefully, use caution so that there is no setback," Marin told Kicker.
"I have had no calls. A return to the Bundesliga is currently not an issue."