Neymar appeared to be furious after Mbappe chose to take a shot rather than pass the ball for a tap-in during their 2-1 win over Juventus in the group stage game on Tuesday.
"The relationship between Ney and Kylian is very good, and I'm not giving you the run-around," Galtier told reporters on Friday.
"They are together in the training exercises, they are often together in the warm-ups. Yes, there was that match situation. And I discussed it yesterday with Kylian, who I think, I think, has discussed it with Ney.
"I am convinced that Kylian will make more decisive passes to Ney, as Ney is capable of making decisive passes to Kylian. But I haven't felt anything negative since the game in relation to this chance."
PSG, who are second in the French Ligue 1, host Brest in the league later on Saturday.
