Tottenham boss Mauricio Pochettino slams FA over tweet mocking Harry Kane

How damaging is Spurs' trophy drought? (3:22)

Mark Ogden and Dan Kilpatrick discuss Tottenham's continual lack of silverware as Manchester United knock them out of the FA Cup semifinal. (3:22)

LONDON -- Tottenham Hotspur manager Mauricio Pochettino has described a tweet sent from the FA Cup's official account mocking Harry Kane as an "embarrassing and disappointing" way to treat a potential World Cup captain.

The Football Association (FA) have written to both Spurs and Manchester United to apologise after a tweet about the England striker was posted just minutes after Spurs' 2-1 defeat to United in last Saturday's FA Cup semifinal.

After a rare off-day for Kane, the tweet read, "What's in your pocket, Chris" with a video of United defender Chris Smalling saying "Harry Kane".

Pochettino described the tweet, which has since been deleted, as "a shame" and even suggested the FA had damaged England's World Cup hopes by leaving their talisman "sad."

"For me, it was embarrassing and it was a shame because the FA is English football, and Harry Kane is a potential captain at the World Cup," Pochettino told a news conference.

"It was difficult to understand, very very difficult. Of course they apologised about that. It disappointed me that this situation happened.

"But we move on. That is the reality of what happened. Always from day one when I arrived in England I say we need to protect our assets, our English players, the young players.

"We need to give them belief, we need to teach them, to educate, and this type of situation disappointed me a lot.

"Harry was very sad of course. But he's strong in his mind. He moves on and of course we're going to help him and we're helping him to move on about that situation. It was a mistake and he needs to move on quick and not think about what happened in the next few days or the next week."

Speaking immediately after a second consecutive FA Cup semifinal defeat, which ensured Spurs' trophy drought extends to a decade, Pochettino put his future in doubt by saying the club needed more time "with me or another [manager]."

Asked it his comments were a message to anyone at the club, he replied: "It's a long term project. That is not going to change with us or another coaching staff.

"It doesn't mean not with me, because I still have a three year contract. But I think that we need time. It's not a message for someone. It was what I feel and what I told you.

"I am not frustrated. I am not disappointed. I am not sad. Of course, you want to win, have success, win a trophy. I am the first to want to win a trophy but you have to show in reality.

"In practice and in theory, everyone will tell you: I want to win. But to win and to compete is completely different when you compete with sides like [Manchester] United and [Manchester] City. The way we're building our success is fantastic -- it's only time. I want to tell you and our fans that we need more time to arrive that another club can arrive at, with less time, in a different way."

Spurs' defeat to United has raised fresh questions about the mentality of Pochettino's young squad, who have squandered winning positions in the FA Cup, the League Cup and the Champions League this season and fallen short in high-stakes matches in their title challenges in the last two seasons.

"I don't believe it's about mentality," Pochettino said. "Tottenham has shown in the last few seasons it can compete and beat any team -- Real Madrid, Borussia Dortmund, Juventus. And of course in the Premier League.

"Now we achieve this level where we believe in ourselves and we can compete in every single game. Now the last step is to win. We're close, we're not going to give up. When you're close the most important thing is to keep going. Work tougher, working harder and believe. It's not a time to blame. It's a time to back my players and then of course the idea we're developing in the last few years."

Pochettino said it would not be easy for Harry Winks to play again this season as he continues to undergo rehab for a longterm ankle problem, while he is also likely to be without Danny Rose (calf) for Monday's match against Watford. The left-back will return to training on Saturday.