Pep Guardiola's City lead rivals United by eight points, with the Etihad Stadium outfit also receiving plaudits for a free-flowing approach that has seen them net 40 times in 12 league games this term.
However, Mourinho disputed the suggestion that any side plays with more ambition than his own as United prepare for the visit of Brighton and Hove Albion on Saturday.
"[To have] more ambition than we have at home is quite difficult," said the United boss. "I don't know who is more ambitious than us.
"We played against Newcastle with [Paul] Pogba, [Marcus] Rashford, [Anthony] Martial, [Juan] Mata, [Romelu] Lukaku; the full-backs are not full-backs, [Antonio] Valencia and [Ashley] Young are wingers not full-backs.
"So I don't know what you want."
With the Brighton game followed in quick succession by clashes with Watford and Arsenal, United have an opportunity to close in on City, who they face on December 10 – but that is not at the forefront of Mourinho's mind.
"We cannot think about the gap," he added. "We cannot think about the gap to City, to the fifth position. We just have to focus on ourselves and in matches.
"It's probably the first time this season with three Premier League matches in one week, with a couple of days in between matches, but I think every team is prepared for that, even when I look to teams with other ambitions I see fantastic squads so I think the teams are going to cope with the week.
"Obviously, for us, Brighton, Watford, Arsenal is a very important week. But let's focus on Brighton, ninth in the table, good team, difficult to beat, don't concede many goals, have a mix of physicality, aggression, quality, creativity. I think Chris Houghton is doing a great job.
"We must focus on this one. I know we have a good record at home and are strong at home, but the opponent is going to be difficult for us."