Police arrested the alleged culprit, who was described as a Chinese man in his 30s, after they found him on the roof of a nearby building.
But police clarified on Monday that the man was actually arrested for skipping a court date in an unrelated white-collar crime case.
"He is not involved in the acid attack and our investigation continues," a police spokeswoman told the AFP news agency.
"He skipped a court date - that was why he was arrested. It just happened that there was an acid attack on that day in the same area."
It was unclear why the man, a tenant of the building, was hiding on the rooftop.
Since late 2008, there have been at least six acid attacks in several shopping districts across Hong Kong, leaving more than 100 people injured.