"I haven't heard anything, and I don't have any interest," Favre told The Miami Herald outside his home in Hattiesburg, Miss.
Favre, 41, was approached after taking a photo with the Oak Grove High School football team, the same squad he's thrown passes to in recent summers.
The newspaper described the veteran of 20 seasons as moving "slowly and gingerly" and not looking the part of a man about to return for another NFL campaign.
"You're from Miami?" Favre asked The Herald reporter. "Don't you have anything better to do?"
Asked Thursday if he would rule out Favre, Sparano said, "I can't rule anything out, OK. So, I mean, we don't rule anything out. I don't know how you want me to answer that. That'll be all over the news now, too, but I'm giving you the only answer I can give you."
As for Favre, a source close to the Oak Grove football team told The Herald that Favre has not been seen throwing at all this summer, but has logged significant vacation hours in Wyoming.