Five people were pulled from the water and taken to hospital on Tuesday but a 21-year-old man was still unaccounted for more than 24 hours on.
Essex Police said on Wednesday that the force had received notification from the coastguard that the search operation in Clacton had been scaled down.
On Tuesday, a helicopter patrolled the area and police and coastguard boats manoeuvred around the pier looking for the man.
Police said in a statement: “A largescale search was launched after reports of six people being in difficulty in the water close to Clacton Pier shortly before 11am on Tuesday July 19.
“Five people were thankfully brought to shore, however one man, aged 21, has still not been accounted for.
“As the appropriate authority, we are attempting to make contact with the family of the 21-year-old man who, at this stage, is being treated as a missing person.”
The East of England Ambulance Service (EEAS) said four men and a woman were taken ashore and assessed before being taken to Colchester Hospital on Tuesday.
Nigel Brown, communications manager for Clacton Pier, told the PA news agency that the current appeared to have “dragged” a group under the structure.
Staff threw lifebelt rings over the side to help some of those in trouble, he said.