Herrmann has been in impressive form this season and has notched six goals in 24 appearances for Gladbach.
His rise in form has also seen him earn his senior call up to the national side.
But Eberl does not entertain the idea of offloading one of their hottest prospects, and hopes that the 22-year-old and other youngsters will stay with the side.
“We will not be entering into the sale of Patrick in the future,” Erbel told reporters.
“We are building something that I hope the young players feel is going in the right direction.”