Full-back Sagna, 29, had been reported to be dismayed by the terms of the 12-month extension on offer from the Gunners, with the France international said to be seeking an improvement on his £60,000-a-week wages and a longer deal.
Wenger, though, maintains those reports are wide of the mark as he looks to tie up the defender on a new, long-term deal.
"I do not understand these speculations," Wenger said at a press conference ahead of Saturday's Barclays Premier League clash against West Brom at Emirates Stadium.
"He has one-and-a-half year of his contract to go, and we are in negotiations with him to extend the contract which are very positive, so I am quite amazed by these statements because it is completely opposite of the feelings we have with the player, and with the negotiations we have about his extension."
Walcott will miss Saturday's match because of a calf injury.
The England forward, 23, will be out of contract at the end of the season, and there has been speculation he will be sold in the January transfer window.
Wenger said: "With Theo, I have no news. I personally am not involved in that directly, indirectly of course yes, but at the moment we have not made any progress.
"Honestly, I am frustrated. Between the player and me it is all clear, he knows what he wants and he has to make up his mind."
Wenger added: "We have been in negotiations with Theo for a long, long time, and we have not been late in our renegotiations with him. We always try to extend the contracts very early."
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