Doc ranger Jim Fyfe said the dolphins were spotted at St Leonards heading up the harbour towards the city at 9am.
"If you are out in the harbour boating today, treat them with respect and give them space," Mr Fyfe said.
He recommended no wake speed within 300m of the dolphins.
"We had a few complaints when they were in the harbour last time (last week) of a jetski moving in among them, we don't want any repeats of that sort of thing."