Supporters of the Save Our Nurseries campaign group have collected signatures for a petition calling for the early years settings in Tower Hamlets to remain open.
Tower Hamlets Council says it costs more than £1m a year to run the three settings.
Under the proposals, which now form part of a public consultation, Mary Sambrook Day Nursery will close next month, followed by John Smith Children's Centre in December and specialist deaf unit Overland Nursery next year.
The council says the nurseries are not cost-effective, costing £15,000 per child compared to an average spend of £1,700 per child in nursery schools.
Nearly 70 children, many of whom have special educations needs and disabilities, are cared for by the nurseries, two of which are based in children's centres.
Click link below for related CYP Now content:
Analysis: Five ways councils can get more from 30 hours funded childcare
Analysis: Mapping children's centre cuts
The settings are funded by the government and parental fees, but also receive top-up money allocated from Tower Hamlet's school budgets.
"School representatives have decided this funding cannot continue, as government cuts and changes to funding mean that schools have much less money," the council said.
"This means the existing top-up funding for the day care nurseries in question will end in September 2018. When this happens, either the council must meet the funding gap by making cuts elsewhere, or the nurseries will close," it added.
However, Tower Hamlets Unison, which started the petition, is calling on the council to undertake a review of the nurseries' management and to develop a plan to ensure their viability.
A Save Our Nurseries spokesperson said there was widespread support for their campaign.
"Having good nurseries in Tower Hamlets is a vital part of investing in our citizens of the future," she added
The council said by closing the "small but expensive council day care nurseries", it would be better placed to protect other early years services which benefit more children.
A total of 27 staff working in the settings earmarked for closure would be offered support, including training and professional development, to help them find new employment, it added.
The consultation, which launched on 19 July, will run until 10 September.
