Ekstrom impressed the Red Bull team on his oval racing debut at Richmond earlier this month, when he finished 31st.
Both team and driver stated their desire to link up again in the future after the race, but Audi has played down the possibility of Ekstrom returning to America.
"For me, this issue is finished," head of Audi Sport Wolfgang Ullrich told AUTOSPORT.
"Mattias did not ask me for another [NASCAR] race - we never talked about it. I think he gave a clear statement that for him the NASCAR experience is done.
"If he does ask to go back, then we will see what it is and what it means."
AUTOSPORT understands that Red Bull has targeted recruiting Ekstrom for multiple races between now and the end of the season.
For more on Ekstrom's NASCAR position, read this week's AUTOSPORT magazine, available in digital form here.
Ekstrom expects NASCAR return soonVilla to hold Valencia talks
