Wigan boss Roberto Martinez apologised to his Wolves counterpart over the spitting incident.
McCarthy said: "What happened is unacceptable. I have spoken to Roberto and he apologised on behalf of the club.
"I don't think that is indicative of Wigan, of Roberto or Dave Whelan (club owner). They are lovely people, a lovely club, and I think he (Alcaraz) has just made a mistake.
"I don't know where it came from but he's made a stupid mistake and got punished with a ban, and we all think that is right."
McCarthy added: "Personally, I'd rather have a smack in the mouth than be spat upon.
"It's the worst thing you can do to a fellow professional. He will be regretting it now and will have to take the consequences."