To dream of an alligator, unless you kill it, is unfavorable to all persons connected with the dream. It is a dream of caution.
Threatening you: fear of an unpleasant reaction to something you said or did.
Not threatening: realization that there are consequences to your actions. Also, that you are prepared to fend off any threats against you.
Attacking you: You have suffered repercussions from previous deeds, or are stressed out about it happening soon.
Alligators most always symbolize a problem! To kill or conquer one means you have overcome a problem. To be surrounded by one means you have to choose one bad thing to get out of a lot of bad things. (any way you run you will encounter at least one). To be eaten or killed by an alligator means the problem that is haunting you is likely to do you harm if not cured. To have a pet alligator symbolizes great control over one's problems.
Being attacked by an alligator in a dream is a sign that you will be laughed at by people who do not like you. Seeing alligators in a zoo is a prediction of a short journey.