Honolulu Mayor Kirk Caldwell said Thursday he might impose up to $1,000 fines or jail time for the owner and users of Lime electric scooters for illegally parking the rental vehicles on public sidewalks.

Caldwell made the announcement at Honolulu Hale five days after California-based Lime initially parked about 200 of its scooters on sidewalks around Waikiki, Ala Moana and Kakaako.

Since then police impounded 96 scooters, which the city said were obstructing sidewalks, as well as scooters on private property in response to complaints.

“It is very troubling to me,” Caldwell said, claiming that Lime had no meaningful discussions with his administration about acceptable and safe implementation of its plans before it started operating. “They gotta stop.”

Lime recovered the 96 impounded scooters from the city late Thursday.

Caldwell said Lime was entitled to retrieve its impounded scooters but that police will continue to pick them up if they are parked on public sidewalks. The mayor said police have better things to do than round up scooters, yet he won’t allow a company to clutter up walkways, especially in Waikiki where sidewalks are already crowded.

Acting Assistant Police Chief Allan Nagata added, “We need to keep our sidewalks free and clear for pedestrian use.”

Lime said in an emailed statement Thursday evening, “We believe in the importance of working with City officials, as we have strived to do in the city since day one. Given the administration’s recent comments, we are conducting our own legal review to determine next steps out of caution for our users and employees.

“In just the past several days, over 4,000 rides have been taken on our scooters, a number that far surpassed our most optimistic projections even with a limited fleet,” Lime said. “We believe this clearly demonstrates a demand in Honolulu for the service we provide, and we look forward to working both with the City Council and the Mayor’s office on finding the best path forward.”

Lime riders use a mobile phone app to locate, unlock and pay for the scooters, which cost $1 to start and 15 cents a minute to operate. The company picks up the scooters at night and recharges them before putting them back on sidewalks in the morning.

Wes Frysztacki, director of the city Department of Transportation Services, informed Lime in a May 9 letter that the city regarded the scooter rental business as a concession not allowed on city property without permission.

Two days later, on the eve of its scooter deployment, Lime responded by saying it had researched relevant city code and believed its “responsible scooter pilot program is permitted, so long as it is safe and consistent with local ordinances.”

On Thursday city officials offered two new justifications for why Lime can’t do what it is doing.

First, the scooters under state law are categorized as mopeds, which can’t be parked on sidewalks, according to the city.

Second, the scooters are also generally defined as vehicles under state law and can’t be parked on any part of a roadway, including sidewalks, for the purpose of selling the vehicle or any service therein and thereby creating a hazardous condition or public nuisance, the city said.

It is this second statute that allows up to $1,000 fines or 30 days imprisonment.

Caldwell said he would prefer not to penalize tourists or other riders who violate the law by parking Lime scooters on sidewalks, but city Corporation Counsel Donna Leong said penalties could be imposed on those who park the scooters, whether it be the company or riders.

“This is a serious offense … and it’s because of the safety hazard that it creates to the general public,” she said. “It is important to keep pedestrians safe on the sidewalk.”

Leong sent a letter to Lime via email Thursday explaining the city’s determination that the scooters are mopeds based on engine power, two wheels and for riding. Leong’s letter also said that the scooters need to be registered with the city and issued license plates.

Caldwell did offer an olive branch of sorts to Lime, saying he’s willing to meet with company officials to explore a possible solution that would allow their business to work.

But the mayor was skeptical about such a solution given what he has heard from mayors in other cities about scooter and bike rental operations that don’t use fixed racks. Caldwell said he’s aware of a lot of problems with riders leaving bikes and scooters haphazardly in places they shouldn’t be in cities including Dallas, San Francisco and Seattle. He also said he doesn’t know of any city with a workable operating model for dockless bike or scooter rentals.

Caldwell noted that it took much time, planning and coordination for the Honolulu bikeshare program Biki to start. Work with the city on Biki dates back to at least 2012. The city granted Biki $1 million and provided a street usage permit for the program where bikes are locked into racks from which they must be rented and returned. Nonprofit BikeShare Hawaii manages the operation, which started in June and has about 1,000 bikes between Chinatown and Diamond Head.