Coutinho arrived at the Bundesliga giants on loan from Barcelona in August, but his impact has been questioned.
The Brazilian, 27, has scored three goals and provided five assists in 17 games for Bayern, who are fourth in the Bundesliga.
But Flick, who will remain as coach until at least the end of the year, said Coutinho deserved more chances.
"Sometimes I think it's good to give someone a little time," he told a news conference on Friday.
"[Coutinho] hasn't been here that long. He didn't have a full pre-season and came to us without much preparation. He went through a change of coach. That's why you just have to give him time.
"He's done well. He scored a goal in Dusseldorf and assisted another. In Belgrade, he assisted two goals.
"In the end, his assists add to his statistics and that's why I'm already satisfied with him."
Bayern host Bayer Leverkusen in the Bundesliga on Saturday.