Around 100 people took part in the protest
The Conservative-run county council has agreed to make savings of £42.5m in the next financial year following a drop in funding from the government.
It means 29 out of 44 libraries across Suffolk could close to save money.
The protesters stood outside Saxmundham library and held a demonstration at the town’s county council office.
Retired teacher Jennie Pink said she had gathered 1,400 signatures on a petition which is calling for the council not to close any libraries.
“I’ve grandchildren in Norfolk [which has] no library closures. Essex said they were going to think about less opening hours,” she said.
“Suffolk wants to divest 29 out of the 44, which is a step too far.
“They could make the cuts, not closures.”
Council leader Jeremy Pembroke has said its budget, which was approved on Thursday, is not of the council’s making but the authority has to “steer Suffolk through challenging times ahead”.