Independent TD Mattie McGrath and five others are occupying the Friends First Finance Headquarters in Loughlinstown in Dublin this afternoon.
In a statement, Deputy McGrath said it was in response to an incident in Co Wexford last week.
The South Tipperary TD said a family was left 'terrorised' by the incident.
The group is seeking a commitment from the bank that it will not send agents to carry out repossessions, which it claims ignores the Code of Conduct for Business Lending to Small and Medium Enterprises.
The group said that it will stay in the building until such a commitment has been made in writing by the bank.
Mr McGrath said: "The family are devastated. I saw them on Friday night, they need support, two young children had left the house, their younger children, young girls, when I went to see them on Friday.
"We want a guarantee that they can sleep in their house over Christmas in relative peace and left alone.
"This is a democracy we are supposed to have, the public are bailing out the banks, not these banks but other banks, and the banks are meting out his treatment to Irish citizens. It is unacceptable and it has to be called to a halt."
Friends First Finance later issued a statement describing the incident which led to the protest.
The financial istution maintains that it has "has acted legally at all times and is not in breach of any Code of Conduct".
Friends First Finance statement in full:
Friends First Finance can confirm that official Salvage Agents acting for the company attempted to repossess a tractor on Thursday, November 29 in Co Wexford.
This vehicle was acquired using funds advanced by Friends First Finance under a hire purchase agreement.
The repossession was made necessary because of the persistent failure by the borrower from the commencement of the agreement in 2007 to honour the repayment terms of the agreement.
Following the borrower’s failure to honour several revised payment schedules, the hire purchase agreement was terminated by Friends First Finance in 2010. While the borrower has repaid a small proportion of interest he did not adhere to the repayment schedule or agreement from the commencement of the contract to date.
Agents acting for Friends First Finance made a legal attempt to repossess the vehicle, on behalf of the company, however successful attempts were made by the borrower and his associates to stop the legal repossession.
The agents made it clear to the borrowers that they were acting lawfully on behalf of Friends First Finance and that they were in possession of a ‘bearer letter’ from the company which gave them authorisation to carry out the repossession on behalf of Friends First Finance.
Tensions arose on site and the agents disengaged from the repossession attempt and contacted local gardaí who attended at the scene and took statements from all parties.
Friends First Finance will always work with borrowers who are having difficulty meeting repayment and the company is willing to have a face to face meeting with this customer to see if a common, mutually agreed, approach can be reached regarding the liability owing to Friends First Finance.
This could form either agreed payments over an agreed period of time, an agreed reduced settlement based on the customer circumstances or in some cases a partial return of equipment with the remaining balance paid over an agreed term.
This is a common approach that we offer to all customers who have found themselves in a severely distressed position.
Friends First Finance has acted legally at all times and is not in breach of any Code of Conduct.