Mayor Gavin Newsom requested last month that the ID card plan - closely watched by other cities considering similar initiatives - be suspended "until a thorough review has been completed," according to a letter sent to the city administrator.
"The mayor wants to proceed cautiously with this program to ensure that it complies with all applicable federal and state laws," Nathan Ballard, the mayor's spokesman, said Thursday.
The plan has provoked debate over the rights of immigrants, but Newsom has said he sees it as a practical move that will make it easier for San Francisco citizens to qualify for local services and for city government workers to determine who is eligible to receive them.
The law, which was scheduled to take effect at the end of August, was modeled after a program launched in New Haven, Connecticut. Similar initiatives are under consideration in New York City and Miami.
San Francisco's policies toward illegal immigrants have come under intense scrutiny after it was revealed that a number of juvenile offenders were shielded from deportation because of the city's sanctuary policy.
Newsom reversed the juvenile offender policy in May, but said he stood by the city's vow to shelter illegal immigrants who otherwise follow the law from deportation.
The ID card plan is the target of a lawsuit filed by the Washington-based Immigration Reform Law Institute, which argues that the city approved the program without accounting for the environmental impact that the influx of new immigrants would have on the city. City Attorney Dennis Herrera plans to ask a judge later this month to toss out the lawsuit.
By Associated Press Writer Jason Dearen