Mourinho backtracked on his pledge to lead United to the top four by January after finding his side 16 points behind league leaders Manchester City 14 games into the campaign.
United, who have a goal difference of minus one, host top-six rival Arsenal on Wednesday, with their opponents eight points ahead in fourth place, as they seek their first league win since November 3.
“I can agree Manchester United should never be in seventh, in spite of the phenomenal investment Everton made and obviously the great improvement in their team from last season,” said Mourinho.
“But I don’t think Everton is going to be in front of Manchester United by the end of the season. I think clearly everybody knows that there are six teams that should all of them stay in the first six positions.
“Everyone knows that two of these teams are staying outside the top four, last season it was Arsenal and Chelsea and this season two of the six are going to stay outside of the top four.
“Who is the best team of the six? Who is the team with the most potential? Who is the team with the least potential? Who is the team that is performing better? Who is not performing so well?
“I think we will be around the questions and the answers, but I think in the end of the season top six will be done by the six we all know to have the responsibility to finish in the top six.”
Mourinho, speaking after Saturday’s 2-2 draw with Southampton, told Brazilian outlet RedeTV it would take a “miracle” for United to finish in the top four.
Asked about his remarks, he said: “I don’t know if I say or if I didn’t but if I used that word is not what I feel at all. We have like eight or nine points from fourth, I don’t think we need a miracle at all.
“We need a good run of results, not waste points we shouldn’t waste. Last week before Crystal Palace game I told my hopes and targets were end of December to be in that position.
“The target change but in the sense let’s try to close the distance best we can and be very close to these positions, I think far from a miracle, we just need to not be so unlucky with problems that we have, we need some players to perform better than they are we need to perform better as a team but far from a miracle.” skysports