In a statement, the authority noted it has already conducted inspections and publicity campaigns, alongside the Immigration Department, at various tourism hotspots over the past two days.
It said they have visited popular areas such as the West Kowloon Cultural District and the Avenue of Stars to distribute leaflets urging people not to follow unlicensed tour guides.
It reminded tourists to check on the business qualifications and licensing status of an agency before embarking on any of its tours.
It also called on visitors to file a report to either the authority or the police if they are treated unfairly by merchants or encounter suspected illegal tour guides.
The TIA also noted that unlicensed tour guides face fines of HK$50,000 and up to a year in prison.