Kane was shut out in the semi-final with Dele Alli and Christian Eriksen linking up to provide Spurs lone goal of the contest while Alexis Sanchez and Ander Herrera netted the goals for the Red Devils.
After the match, the FA Cup’s official Twitter account posted a message asking United defender Chris Smalling what was in his pocket . Then attached was a second long clip of Smalling saying “Harry Kane” to something unrelated.
The tweet was eventually deleted.
On Monday, the FA announced it had apologised to both teams over the incident.
"We have written to both clubs to apologise for any offence caused,” an FA spokesperson said.
Kane has been the subject of many jokes over the past two weeks since successfully winning an appeal to claim a goal originally credited to Eriksen in Tottenham’s victory over Stoke City.
Most of those jokes have involved players, fans or clubs, warning of or announcing a goal scored would soon be credited to Kane.
It was even noted during the semi-final itself as after Alli and Alexis' goals, Wembley Stadium’s official accounted tweeted: “If anyone says Kane, they’re getting blocked,” when asking which goal was better.
If anyone says Kane they’re getting blocked https://t.co/SZCEQJymG6— Wembley Stadium (@wembleystadium) April 21, 2018