The 22-year-old has impressed in the Premier League since making the move to Swansea in January, scoring seven goals in 15 appearances.
However, Jenkins believes that the Welsh side face a fight to convince Hoffenheim to sell their young midfielder.
"He's done a great job for us and is still only young. Our aim is to keep our best players. We've always tried to do that over the years and it will be no different with Gylfi," Jenkins told BBC Radio Wales.
"The fact is when you take a player on loan, control is out of your hands. Hoffenheim wouldn't commit to a deal before we took him, which we would have loved to have done.
"No doubt there's going to be a bit of a battle on our hands to secure his services for next season."
Swansea currently sit 12th in the Premier League table.