The highly rated 20-year-old has been a regular for Freiburg, making 25 appearances this season.
His form has seen him linked with a move to the Emirates Stadium and Signal Iduna Park and Freiburg will be powerless to keep him if they are relegated to the second tier.
Despite a 4-1 win at Eintracht Frankfurt on Saturday, Freiburg occupy the relegation play-off place in the Bundesliga table.
However, Keller feels Ginter would be better suited by staying at Freiburg and getting first-team football instead of warming the bench at another club.
"He has a long-term contract and for a player his age, it may be interesting to stay another year for stability," Keller told Badische Zeitung.
"This is in my opinion better than to sit on the bench for one of the big clubs."
Despite wanting to keep Ginter, Keller admits that players leaving the club is something that cannot be avoided, given Freiburg's lack of financial clout.
A new stadium will help Freiburg keep hold of their best players though, he believes.
"We must always expect players to leave us," Keller added.
"Turnover is normal for us, as we have seen recently, but we do our homework. Sure we can continue to do this, but it is important that we get a new stadium. Then we can keep players maybe a year longer.
"A stadium is not a luxury, but important in the struggle for survival."
