Not by usual standards of what a "word" is. It is a communicative sign, but there are tons of sounds that you can make with the face or other body parts that convey something, and "words" are not simply "communicative signs". A word is part of a rule-governed linguistic system of coding. Consider the difference between an actual imitation of a cow mooing, which I'll write as *MOO*, and the word "moo". You can say "The cow is mooing", but you can't say "The cow is *MOO*ing". There are myriad created words that represent communicative sounds, such as "brap" for "*BELCH*". Although they are marginal as words, there are words that stand for the clicky sound of disapproval, namely "tisk" and "tut".