Although Duff only called time on his 100-cap career just over two weeks ago, Trapattoni and his assistant Marco Tardelli both said last week that they were hopeful of seeing the winger pull on a green shirt again. Trapattoni hopes to speak to Duff tonight after the Republic's friendly against Oman at Craven Cottage, where the 32-year-old plies his trade with Fulham.
But Doyle, who will skipper the side against the Gulf state, said: "I think from what I have heard Duffers is well and truly in the retired camp. I think he wants to be left alone for a while."
Trapattoni has made 10 changes to his line-up for the match against Oman, with David Meyler and Robbie Brady both making their first appearances for their country.
A number of squad players will also get their chance to show Trapattoni that they can be relied upon should they be required for next month's qualifier against Germany.
Stephen Kelly will start alongside Paul McShane in central defence having been left out of the team for Friday's fortuitous 2-1 win in Kazakhstan. The 28-year-old hopes to impress the 73-year-old on his 31st outing for his country.
"Hopefully we will get a win and for me it will be a chance to show the manager what I can do," Kelly said.
"Whenever I have been called upon for the qualifiers I have given it my all so I'm glad I'll get a chance to remind the manager what I can do.
"The pressure was on us against Kazakhstan so hopefully there won't be as much pressure for the Oman game and for me it helps that it's at a ground I'm obviously familiar with."