The 19-year-old Argentina international posted a photo of players congratulating Onana for stopping a penalty late in United's 1-0 win over Copenhagen in the Champions League on Tuesday.
Garnacho used two gorilla emojis above the photo in a post on X, formerly known as Twitter. It was then deleted.
Onana, who is Black, wrote on his Instagram Story that he understood what Garnacho meant.
“People cannot choose what I should be offended by,” the Cameroon international wrote on Thursday. “I know exactly what (Garnacho) meant: power & strength. This matter should go no further.”
The Football Association could still take action, however.
Onana also posted a photo of himself and Garnacho hugging, and he added two fist-bumping emojis.
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