What animated movie is this?

Ok It`s been bothering me because I can`t remember the name of this older cartoon-movie, and I can`t find it anywhere either. The only things I remember is the race of monsters in it. the had somewhat pointed ears kind of looked like a bat. There feet were like stone feet or something like that, I remember a guy sneaking down to their portion of the city to save a girl, and he ran into a old female monster who was sleeping and he hurt her feet or something like that. and a part where one of the monsters is standing behind a curtain. I know it isn`t much to go on but I watched it when i was younger and its been botherin me, not knowin the name. Any help would be appreciated