With defender Shkodran Mustafi's tournament over after he suffered a torn thigh muscle in Germany's last-16 tie, Lahm had been tipped to drop back from midfield to a more familiar full-back role to fill the void against France in Rio.
Lahm occupied the right-back position after Mustafi succumbed to injury during Germany's extra-time win over Algeria, with Sami Khedira replacing the Bayern Munich captain in midfield.
But speaking to German newspaper Die Zeit, Low insisted that the 30-year-old will continue in the centre of the pitch, with utility man Kevin Grosskreutz seeming to be the most likely to start in defence - youngsters Matthias Ginter and Erik Durm are the other options.
"I have made up my mind already on Philipp Lahm's role," Low told Die Zeit. "And I am sticking by it to the very end.
"Philipp Lahm has been a leading figure for us in recent years and he's been playing at the highest level for a decade, but he will only move back into defence if we have a problem on the right, at which point I might say 'okay, now it's up to Philipp who can push forwards down the right.'
"But that would only be an emergency scenario, and we need to prevent there being an emergency."
The German coach also leapt to the defence of Mesut Ozil, who has struggled to make a significant impact since being deployed on the left-hand side of midfield in Brazil - away from his usual playmaker role.
"Mesut is extremely important to us," Low added. "The criticism of him is just as incomprehensible as that for Lahm.
"Sometimes things get published a little too hastily and I don't feel the right weight is given to certain things."
