Only individuals living in the same household are allowed to sit together at restaurants, and masks are required whenever people aren't eating or drinking.
If anyone is found without a mask, volunteers will provide them with one, according to city officials.
Newsom announces new, regional stay-at-home order in California
Refusal to follow the rules could result in a citation.
The city, whose COVID-19 guidelines have been less restrictive than those of Los Angeles County, on Tuesday announced new limits on activities after inspectors caught multiple violations of health protocols.
Pasadena has its own health department, as does the city of Long Beach, so it is not subject to the county's limits on dining, gatherings and other activities.