The African nation appeared to have rescued a point in Natal on Monday when Andre Ayew cancelled out Clint Dempsey's first-minute opener in the closing stages, only for American defender John Brooks to head a dramatic winner.
Ghanaian news website Joy Online reported a scheduled Tuesday press conference was cancelled amid player unrest, naming experienced midfielders Sulley Muntari and Kevin-Prince Boateng among a group of players unhappy with the tactics employed by Appiah during the 2-1 Group G reverse.
Schalke's Boateng only featured as a 59th-minute substitute and Joy Online said: "Kevin is on record to have criticised the tactics by the coach. He said he was surprised he was kept on the bench when he should have started."
However, the Ghana FA subsequently took to its official Twitter page to reject the story, which was carried by Joy Online, its associated radio station and other media outlets.
They tweeted: "@ghanafaofficial rejects as false, reports by Joy Fm, Graphic & Citi FM claiming there is player revolt after the defeat to #USA.
"@ghanafaofficial all players have turned up for training and (are) poised to face #GER (Germany). They are focused on #FifaWorldCup."
Ghana take on Germany in Fortaleza on Saturday and will close the round-robin phase by taking on Portugal in Brasilia on June 26.
