Mbappe joined the LaLiga and Champions League winners as a free agent from Paris Saint-Germain in June, bringing an end to a transfer saga that had rumbled on for years.
Despite making a promising start by scoring on his debut to help Real earn a 2-0 win over Europa League champions Atalanta in the UEFA Super Cup final two weeks ago, Mbappe has yet to find the net in two LaLiga games with Real and struggled in a draw at Mallorca and in a dour home win against Real Valladolid.
"His last goal was on August 14th. It has only been two weeks since, that is no reason to worry. Neither we are not worried as a club, nor him," Ancelotti told a press conference on Wednesday, ahead of Thursday's LaLiga match at Las Palmas.
"He is very happy here, delighted, sure he wants to score in the next game. So does Vinicius, who has yet to score this season and I don't see him worried either.
"(Mbappe) is progressing really well, I see him doing better every day, excited, motivated, training well. He is very humble. I think his adaptation is going really well."
Ancelotti said a slow start was to be expected after key midfielder Toni Kroos retired, while they are also trying to fit Mbappe into a new centre-forward role.
"Every year has its own challenge because there are changes in the structure of a team, the system that is implemented," Ancelotti said.
"Last year we also needed time at the start of the season, we needed a late goal to get a result in many games. It will take some time until we find our mojo and the best version of ourselves but it's a normal thing.
"I didn't ask Toni Kroos to be Aurelien Tchouameni last year, just as I won't ask Tchouameni to be Kroos. Each player has his own characteristics. The team has to adapt to the characteristics that Tchouameni has, which are very important for us."
With a game in hand, Real Madrid are fifth in the LaLiga standings on four points, five behind leaders Barcelona.
