Cavani deleted the post, sent to a friend on Instagram, after being made aware of the meaning in the UK.
The 32-year-old scored twice — including a stoppage-time winner — as United came from 2-0 down to beat Southampton 3-2 on Sunday.
Sources have told ESPN that Cavani meant the phrase as a term of affection in response to a message of congratulations following the result at St Mary’s.
Cavani has explained to United that he was unaware of the meaning in the UK because it is used among friends in his native Uruguay. It is likely to be his defence if he faces an FA charge.
The FA found the tweet constituted an “aggravated breach” of the Football Association’s rules on social media behaviour and Silva was also ordered to undergo an education course.