The delay means enforcement cannot begin until mid-February at the earliest, but City Council members said they wanted more time to consider restrictions on where dispensaries can be located.
The draft ordinance requires them to be at least 1,000 feet from buildings with residential uses, but City Council President Eric Garcetti called that a "well-intentioned plan that may have bad consequences."
He warned it could result in the city having only "about five or ten mega-dispensaries that would be in industrial parks in Los Angeles, and that's it."
The Wilshire district, with a population of 600,000, is one of the most densely populated communities in the United States. But Garcetti said it may not be allowed to have any dispensaries at all under the proposal.
"You're pretty much obliterating the ordinance," said Councilman Jose Huizar. "We might as well not have an ordinance."
Don Duncan, California director for Americans for Safe Access, has also warned that the residential restriction could result in "de facto ban on medical cannabis in Los Angeles and that's contrary to the will of the voters, and it's contrary to what the council has expressed at its intent."
But Councilwoman Jan Perry, who introduced the 1,000-foot buffer between dispensaries and homes as a last-minute amendment, stood her ground.
"I think it provides that barrier that is clear cut, easy to understand, and easy to enforce," Perry said.
The City Council needs at least 10 votes to pass the ordinance. Only 11 members were present during Wednesday's session, and at least two of them -- Perry and Councilman Greig Smith -- said they would reject the ordinance if the residential restrictions were taken out.
Councilman Ed Reyes proposed delaying the vote until January, by which time the Planning Department should have prepared maps that would show the specific areas where dispensaries can open.
Reyes said the postponement "breaks my heart because I wanted so much to get this done," but added it would be more prudent to wait for the maps to be completed.
A frustrated Councilman Richard Alarcon lashed out at the proponents of the residential restriction, saying "to waste all of our time with the intent of throwing a poison pill into the final process is demeaning to the process."
The draft ordinance would cap the number of dispensaries citywide at 70, but would allow almost double that number to stay open -- at least temporarily -- provided they adhere to the new restrictions.
The City Council granted a reprieve to 137 dispensaries that opened before a moratorium was declared in late 2007. If any of those dispensaries closes down or goes out of business, it will not be replaced until the overall number is reduced to 70.
Dispensaries that opened after the moratorium by taking advantage of a legal loophole would be shut down 30 days after the ordinance was passed.
Officials estimate that between 800 and 1,000 dispensaries are operating in the city, most of them illegally selling marijuana for recreational use.