"I’m not aware. Nothing happened. Nothing at all," the Frenchman told reporters ahead of Arsenal's Champions League last 16 second-leg match against Bayern Munich at the Emirates on Tuesday.
"(The media reports are) completely false. But I understand that you have to fill the newspapers and we respect that," added Wenger.
Reports in Monday's papers said Sanchez was dropped from the starting line-up for Saturday's 3-1 Premier League defeat at Liverpool after the 28-year-old allegedly rowed with the manager and team mates.
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Wenger brought on the Chilean at halftime with Arsenal, who are now out of the top four in the Premier League, 2-0 down at Anfield.
"I explained after the game at Liverpool that I decided to go for a more direct option in the game and that's what happened. That was the unique reason for my decision," said Wenger of his tactics.
"For the rest, his attitude...He is a committed player, sometimes with excessive behaviour, but you have seen that many times in history in every squad."
Responding to questions about Sanchez's future at Arsenal, with mounting speculation that the player could leave at the end of the season in a big-money transfer, Wenger said it would be the club that decided.
"Alexis Sanchez has 15 months on his contract so the decision will depend completely on Arsenal football club, not anyone else," he said, describing his relationship with the forward as "honest and normal like with every player".
The manager added that the most important thing was to perform as a team.
"Players at that level are proven but football is not about one player, it's much bigger than that," he said.
Sanchez, Arsenal's top scorer with 17 league goals this season, trained with the rest of the players at London Colney on Monday and was photographed shaking Wenger's hand.
Arsenal were trounced 5-1 by Bayern in the away leg and will have to produce the biggest second-leg comeback in a Champions League knockout tie to avoid a seventh successive exit at the last-16 stage.
(Reporting by Alan Baldwin, editing by Ed Osmond)
