First of course, you will need a car registered in Florida to obtain insurance. If you are going to be in Florida for an extended period of time you might think about obtaining a Florida Driver's License. Most insurance companies will allow you to purchase auto insurance with an International Driving Permit but require you to obtain a valid US license within a certain period of time - 30 to 45 typically or the policy will cancel.
According to Florida law anyone who has a vehicle in Florida for more than 90 days must purchase personal injury protection and property damage liability insurance coverage. This minimum insurance must be issued through a Florida agent with an insurance company licensed to sell in Florida.
For your auto insurance needs in Florida we can try to help you obtain the coverage you need so you can enjoy your vacation in the U.S.