On the eve of Bonfire Night, it was revealed Strathclyde Fire and Rescue (SFR) crews have come under twice in the past week.
Senior fire officers have warned that anyone involved in violence against crews would "feel the full force of the law".
Crews were attacked in Torogay Street, Milton, about 6.30pm on Wednesday night, after being called to a bin fire. Missiles were thrown at the vehicle.
And last Thursday firefighters were attacked by a group of youths brandishing wooden batons, bottles and poles in Cumloddin Drive, Maryhill, about 10.30pm.
As well as having projectiles thrown at them, they were verbally abused. No-one was injured and no damage was caused to the fire engine.
One youth has been charged in connection with the incident.
SFR Assistant Chief Officer and Operations Director David Goodhew said: "Any attack on a fire crew will not be tolerated. These firefighters were doing their jobs, responding to a call about a fire, and set upon by a gang.
"Fortunately, no-one was hurt in this mindless attack, but it's only a matter of time before a firefighter is seriously hurt, or even killed, in such an incident.
"We operate a zero-tolerance policy on attacks on our crews and will continue to work closely with the police to identify anyone involved in such attacks."
He said, with Bonfire Night approaching, SFR has a simple message for anyone who is thinking of using this time of year to target firefighters: "If you attack our crews, the authorities will find you, you will be prosecuted and you will feel the full force of the law."
Inspector Ross Allen, of Maryhill Police Office, said Strathclyde Police enforce a zero-tolerance and robust approach to any instance of violence, disorder or obstruction against their partners in the emergency services.
He said: "We will ensure that no opportunity is missed to detect and apprehend any person or persons found committing such mindless acts."
John McKenna, station commander at Maryhill, said their crews had been proactive: "We have been scouring the area for bonfires which have been built and have had them removed before they can do harm. Many more will be built within the next 24 hours."
A Glasgow City Council spokesman said they work with the fire service and other agencies to identify unauthorised bonfires and, where possible, dismantle them.