The Portuguese says the Gunners have made fewer mistakes and warrant their position, and also feels that Manchester United will not panic despite falling 12 points behind.
Arsene Wenger's men are currently four points clear of Chelsea and welcome high-flying Everton on Sunday while the Blues travel to the Britannia Stadium to take on Stoke City.
However, Mourinho feels there is a long way still to go in the race for the title and also reiterated his belief that Manchester United still remains a threat despite falling 12 points behind the Gunners.
"In relation to Arsenal - if they lead, it's because they were better, made less mistakes," he told reporters. "So they deserve to be there. But the championship doesn't end at the end of the year, it ends at the end of May.
"If it's another club [other than United] I would tell you it's impossible. With Manchester United I don't say that. The potential and the culture of the club is not one to panic.
"They are still a contender; they will stick together, win five or six matches and they will look to other matches where teams will lose points."The Portuguese has also hit out at his club's current hectic schedule, insisting other sides are having more chances to rest than the Blues.
"This week was a hard one. We started on a Sunday, not a Saturday, playing against Southampton and finishing on Saturday [at Stoke]," he said. "For some clubs it's Saturday to Sunday, for us it's Sunday to Saturday. For us, again, when it comes to fixtures we are in trouble.
"[It would be] a big coincidence; it's always the same teams; the situation always benefits the same teams. We have had three matches, two of them consecutive away. We have to cope with it and give a big effort.
"I don't like to give a day off before a Champions League game, but I'll give the day off on Sunday. It's good for their heads; I like the players to recover from a physiological point of view but mentally (t is more important."