United succumbed to two deflected goals from substitute Xherdan Shaqiri at Anfield, after Jesse Lingard cancelled out Sadio Mane's opener.
Asked if he could fix United's predicament, Mourinho told Sky Sports: "What do you mean by fix? You mean win the title? I can't fix this.
"We can still finish fourth, I think it is not easy, for sure we are going to finish in the top six like all of the other historically top teams, but the best we can get is the fourth position.
"Now we have to look to the fifth position and then probably later the fourth."
26 - Manchester United have picked up 26 points after their first 17 Premier League games; their worst points haul in the top-flight at this stage since 1990-91 (also 26 points). Dip. pic.twitter.com/FI2avHKq1D— OptaJoe (@OptaJoe) December 16, 2018
Mourinho also defended his defensive tactics in Sunday's encounter, stating United cannot realistically compete with Jurgen Klopp's side.
"Liverpool is the better team, we cannot compare their intensity, their physicality, then the technical qualities come up and they are a better team than us," he said.
"In spite of that, we were in the game until we conceded the third, I repeat, in a moment where the most probable result was obviously a draw, because we had as many chances as them to win the game in the last 10-15 minutes."