The Los Angeles City Council on Tuesday voted to place a third initiative regulating medical marijuana dispensaries on the May ballot.

The measure, approved on an 8-4 vote, would sharply reduce the number of medical marijuana dispensaries in the city and impose a steep gross receipts tax on the dispensaries.

The measure is similar to one placed on the ballot earlier this month by a coalition of older dispensaries and the United Food and Commercial Workers Union in that it limits the number of dispensaries to the 127 that were established before a 2007 city moratorium.

On Monday, the coalition announced it was dropping support for its own initiative and would campaign for the city’s measure.

The other ballot measure is principally backed by post-2007 dispensaries; it would allow all dispensaries now open to continue operating and place some zoning restrictions on the opening of new dispensaries.

There are now an estimated 1,000 medical marijuana dispensaries operating in the city. Last July, the City Council, responding to widespread complaints from residents and some neighboring business owners, passed a ban on all dispensaries. The council repealed the ban in September amid concerns that it could be overturned and leave the city without the power to regulate the dispensaries.

Besides limiting the number of storefront dispensaries, the council’s measure would prohibit dispensaries within 1,000 feet of schools and 600 feet from parks, libraries and other dispensaries. It also would place a tax of $60 per $1,000 in gross receipts, slightly higher than the $50 per $1,000 in gross receipts in the dispensary-union coalition’s initiative.