Starting next month, the city plans to enforce new rules intended to clamp down on vendors who operate as religious groups in city parks to sell everything from T-shirts to potato chips.

The new rules went into effect on Friday and are the latest attempt to control commercial operations by groups claiming religious exemptions in public spaces from Waimea Bay to Kailua Beach to Hanauma Bay.

But, since some of the vendors already were issued permits under the old rules for September, “you’re not going to see the actual changes until Oct. 1,” said Nathan Serota, spokesman for the city’s Department of Parks and Recreation.

Each violation carries maximum penalties of a $500 fine and 30 days in jail. The Parks and Recreation Department said it also “reserves the right to seize and dispose of any merchandise being sold or distributed on park land in violation of these rules.”

For September, 15 applicants were granted 81 permits to operate in city parks, including a group that was kicked out of Diamond Head State Park in 2011 and then moved its operations to city parks.

“Quite a few” permits have been issued for Hanauma Bay and on the North Shore at Waimea Bay, Sunset Beach and Ehukai Beach parks, Serota said.

At Waimea Bay Beach Park on Wednesday, a vendor sold T-shirts with words such as “Pipeline” and “Sunset” for $8 apiece, or three for $20.

He declined to identify himself or to be photographed, but displayed a city permit that listed the same Waialua address on Puuiki Street as the group that was issued a cease-and-desist order by the state Attorney General’s office in December 2011 after selling similar items in Diamond Head State Park.

The organization’s president, Dipak Sarkar of Waialua, could not be reached for comment on Monday.

The city’s new rules are intended to ensure First Amendment rights of religion and expression while allowing vendors with permits to set up a table to sell — or distribute for free — so-called “expressive materials,” defined as “any written or printed material containing political, religious, philosophical or ideological messages.” Such materials under the rules include but are not limited to books, pamphlets, handbills, cards, circulars, pictures, magazines and leaflets.

Vendors who do not require a table to either sell or distribute expressive materials for free do not need a permit, Serota said.

At the same time, the new rules specifically ban items such as “food, drink, coffee mugs, beverage containers, sunglasses, flags, records, patches, maps, jewelry, handicraft, decals, audio or video tapes, shirts, hats, ties, shorts, footwear or any other clothing article.”

Technically, the city repealed the old requirements known as the “Rules and Regulations Governing the Sale of Message-bearing Merchandise by Nonprofit Organizations in City Parks and Facilities.” Instead, the city adopted new rules titled the “Sale or Distribution of Expressive Materials.”

State Rep. Cynthia Thielen (R, Kailua-Kaneohe) testified in February on the then-proposed rule changes. On Monday, Thielen said they won’t work.

“They did get a handle on it at the state end, but the city has been absolutely ineffective in maintaining our parks for our local residents and visitors,” Thielen said. “I don’t think these rules are going to change anything. The vendors are smart. They’ll just continue what they’re doing. I’m very disappointed.”

At Kailua Beach Park, where other commercial vendors are routinely turned away, Thielen said she regularly gets complaints about vendors setting up tables on the grassy area makai of the parking lot to sell T-shirts and food.

“It’s unfair,” Thielen said. “It allows a group to set up a commercial operation in the park when others are not allowed to do that, under the guise of religious freedom and First Amendment rights.”

Serota, the parks department spokesman, said the city modeled its new rules under “what’s seen in the state rules and what’s seen nationally.”

Starting next month, Honolulu police will begin enforcing the new rules in city parks, Serota said.

Under the old rules, Serota said, lack of enforcement “was an issue in the past.”