A tweet appeared on the 'Emirates FA Cup' feed showing United defender Chris Smalling replying "Harry Kane" to a mocked-up question: "Chris, what's in your pocket?"
It came moments after the 'Red Devils' had secured a 2-1 victory over Spurs in the semi-final, one in which Kane had failed to make an impact on.
The tweet was shared by thousands of Twitter users and was only removed from their feed on Monday morning, with the private apology sent hours later.
The incident came a fortnight after Kane was in the social media spotlight for claiming a goal that was initially credited to Christian Eriksen during their win over Stoke City on April 7.