Minister for Communications Denis Naughten has rejected claims that the reduction in the number of post offices in the west and midlands will lead to the closure of dozens of small businesses and job losses.
At a public meeting in Athleague, Co Roscommon, Mr Naughten was told the Government decision to allow more than 150 outlets to close their doors was akin to treason in the economy of rural Ireland.
Western counties will be hit hardest by the closures, with at least 45 to close across counties Galway, Mayo and Donegal.
At least 17 are to close in Galway, with six in the east of the county, while five will close in Roscommon.
The plan will see 17 post offices shut in Donegal and 11 in Mayo.
Mr Naughten was told at the meeting that there would be widespread closures of other small business in his constituency as a result.
The minister said An Post was not withdrawing contracts and anybody who wished to stay open could do so, while independent reviews could also be sought.
However, the minister was widely criticised for a failure to support village post offices.
Fianna Fáil TD Jimmy Murphy said the closure decisions would now be negotiated with the Government as part of the future talks on the next Budget.
Mr Naughten told the meeting there was time for post masters to hold further discussions with An Post and have the decision to close their post office reviewed but he said he would not negotiate it in public.
An Post has defended its plan, saying it was trying to ensure the future viability of post offices across the country by improving services.
Chief Executive David McRedmond denied the move was an attack on rural Ireland and said it would be opening five post offices in rural areas next week.
All the post offices facing closure are within 15km of at least one other post office.
Mr McRedmond said the percentage of customers affected is 3.7%, while "96% of people will have better post office services."
Big turnout tonight in Athleague, County Roscommon as locals oppose the closure of 5 post offices in this region . @ciaranmullooly will have a report from here on @morningireland this Thursday on @RTERadio1 #PostOfficeClosures pic.twitter.com/4HFZ1hyKNH— Ciaran Mullooly (@ciaranmullooly) August 29, 2018
Postmistress Imelda Burke, of Ahascragh Post Office in Co Galway, has appealed to people to use the post office and said if they do not they will lose it.
Speaking on RTÉ's Today with Miriam, Ms Burke said she sent a letter to 750 people making the appeal but only three people responded to her first letter.
Ms Burke said she will make a further appeal tomorrow, adding that unless she is proactive about attracting customers, the post office will close.
She said she has told people that the future of the post office rests with the local community. If they don't want to lose it, she said, then they have to start using it.
In a second letter, which she will send tomorrow, she said she has outlined all of the services that people can avail of in her post office.
"Basically I'm telling the public the truth, that the future of their post office rests with the local community. If they don't want to lose it, then they have to start using it as much as they can. And then I went on to list everything that can be done within the post office."