Residents in Whitchurch and Rhiwbina have signed a petition against plans to cut the 21 and 23 bus service between the two villages.
Cardiff Bus proposes to cut the service which currently runs every 20 minutes to one every hour.
This comes as the company undertakes a number of cost-cutting measures including the closure of its customer service centre due to take place on March 29.
Residents are concerned the loss of the service will hit elderly residents who use the service to get to the shops as well as damaging local businesses.
The petition, which currently has more than 509 signatures was created by Mari Williams, parliamentary candidate for Cardiff North.
She said: “At a time when we need to be encouraging people out of their cars, to use public transport, to cycle or to walk. This is a backward step.”
Chris Davis, councillor for Whitchurch said: “I’m fully behind residents on this, but at the same time, services across Cardiff are under enormous pressure.”
In a statement a Cardiff Bus spokesperson apologised for the inconvenience to customers.
He said: “The cuts mean that the revenue we receive for carrying concessionary customers is reduced. As a result, we have had to adapt our services to compensate for this decrease in funding to ensure the long term sustainability of our business.”