The champions, who are chasing a fourth consecutive league title, host Getafe on Tuesday on the back of nine consecutive victories.
A tenth would put them on 78 points from 32 matches, one behind the leaders, who visit city rivals Atletico Madrid on Wednesday after three draws in their last five matches.
"In the history of the league no one has ever overturned a ten-point advantage," Guardiola told a news conference on Monday.
"It is almost impossible for us to be champions. Now everyone seems to think we have them beaten, a team that will break the league goal-scoring record... but four points is still a lot.
"People seem to take it for given we will beat them when they come here [for the 'clasico' in two weeks' time]. Madrid will come here knowing if they beat us they will be champions."
Local media have tagged Real's last seven games of the season, which includes trips to Atletico, Athletic Bilbao and Barcelona, as tougher, but Guardiola dismissed such talk.
"To be champions, we have to win our last seven games, which will be difficult because it means winning 16 in a row," Guardiola said.
"People think it is easy to beat Getafe [one of only two teams to have beaten them in the league].
"I don't want us to go into the [Getafe] game thinking Real are scared and will not stand the pressure. They will be able to stand it because they have great players."
In an attempt to dampen any sense of euphoria, Guardiola fired out a warning to his own players, who have said they believed it possible they could win the title.
"The players know what they have to do between now and the end of the season," he added. "Smile less and run more."
Defenders Dani Alves and Gerard Pique are injury doubts while Barca are awaiting a decision on an appeal over a fifth yellow card for Cesc Fabregas from the weekend, which if unsuccessful means he will be suspended.
