By SABC Sport
26th October 2023
The 19-year-old Argentina international posted a photo of United players congratulating Onana after the Cameroon goalkeeper had saved a stoppage-time penalty in Tuesday's 1-0 Champions League win over Copenhagen.
Garnacho's post on X, formerly known as Twitter, featured two gorilla emojis without any words, and was quickly deleted.
The social media post could land Garnacho in hot water with the Football Association but Onana wrote on the same platform: "People cannot choose what I should be offended by.
"I know exactly what @agarnacho7 meant: power & strength. This matter should go no further."
However, the FA has punished players in the past for making racial slurs on social networking sites.
Former United striker Edinson Cavani was banned for three games and fined £100,000 in 2020 for using the Spanish phrase Gracias negrito' - which translates as thanks little black' - below a friend's Instagram post.
Cavani also underwent a two-hour face-to-face training course for a comment said to be a term of endearment in his native Uruguay.
In 2019, Bernardo Silva was given a one-match ban and fined £50,000 by the FA for his tweet to Manchester City colleague Benjamin Mendy.
Silva tweeted an image of a young Mendy alongside an image of the cartoon brand mascot of Spanish confectionery brand Conguitos, with the caption "Guess who?"
Cavani and Silva were both punished by the FA after deleting their messages.