The Toffees were condemned to their 13th league defeat of the season by Jose Mourinho’s men, in a game which lacked quality and intensity depsite both sides' European qualification ambitions.
Defender Michael Keane turned Giovani Lo Celso's shot past Jordan Pickford after 24 minutes and that was enough to lift Spurs to eighth on the Premier League table.
Ancelotti believes Everton need to change their mentality against top teams and admits the visitors were a bit unlucky.
"We have to change our mentality [against top teams] - that's absolutely normal. We can improve day by day,” the former Chelsea, Real Madrid and Napoli boss told Sky Sports after the game.
The Italian added: “We lost a lot of second balls. We were a little bit unlucky - we could do more. We have to keep on fighting.”
“Tottenham didn't have a lot of chances. It was a battle in midfield. In the second half we created more opportunities. We didn't have many chances but had a lot more possession.”
Everton are still hoping to secure a place in Europe next season.
Ancelotti refused to give up and has urged the Merseyside-based club to keep fighting.
He concluded: "We have to keep fighting - we can have our chance still."
Everton will host Ralph Hasenhuttl’s Southampton at Goodison Park on Thursday evening.
