"Every interview I do, people keep asking me about it and it's more coming from the fact that the manager's talking about it," Kelly said in an interview with the Sunday Independent.
"As far as I'm concerned, Damien's retired. He's a really good friend of mine and he's made the decision for himself and for his family. I think it's strange that they keep going on about it. Not the media. The media keep going on about it because the manager's talking about it. I think it's strange that the manager and staff keep bringing it up. If they have any private conversations with Damien just leave it at that. I think it should be nipped in the bud. The speculation is ridiculous and it's been dragged on for no reason."
Trapattoni has been quieter on the subject since the Oman game last month. Before that, he repeatedly hinted that Duff might be talked out of retirement to face Germany. Duff retired with 100 caps in August and has never given an indication he might change his mind.
"I don't think the manager is privy to any more information than I would be," Kelly added.
"If Damien is going to come back, he's not going to make a big song and dance about it, that's not him but you can see he's happy with his decision. He will do it if he thinks it's right and at the moment obviously he doesn't think it is."
Kelly also expressed his frustration at not playing at all at the European Championships but said, unlike Darron Gibson, that he has never considered not turning up for Ireland. "Darron didn't play when he was over there, that's the manager's prerogative. But there's a lot of us in that position, I think I'm in it more than anyone. I felt I played a huge part in the game that got us to the Euros in Tallinn. I've given a lot to the team. To be perfectly honest, if anyone is to feel aggrieved at not playing, I think I have the strongest case. It's not through my lack of conviction that I'm not annoyed. Of course I am. But the way I see it is, if you don't turn up, you can't play and the only way I'm going to get to play for my country is if I'm there."
Kelly will join up with the Ireland squad this week as Trapatonni faces an injury crisis in defence. Sean St Ledger is unlikely to play having suffered a hamstring injury playing for Leicester City yesterday. He will, however, report to the Irish team hotel tomorrow and will undergo a scan. Richard Dunne is already out with a long-term injury.
Kevin Doyle withdrew yesterday after he picked up an injury in training for Wolves. Robbie Brady, who went off with an injury during Manchester United's under 21 match last Monday, joined David Meyler as a late addition to the squad.