Minister for European Affairs Helen McEntee has insisted a number of measures to avoid a hard border in Ireland have been considered, but have been found to 'simply not work'.
She was speaking amid the ongoing impasse over the backstop insurance policy.
Boris Johnson has insisted any deal must drop the backstop, but that demand has been repeatedly rejected by the EU.
Mr Johnson is in Germany today to meet Chancellor Angela Merkel, before travelling to France for talks with Emmanuel Macron in Paris tomorrow.
However, little progress is expected after European Council President Donald Tusk rejected Mr Johnson's proposals for unspecified backstop alternatives to be considered:
The backstop is an insurance to avoid a hard border on the island of Ireland unless and until an alternative is found. Those against the backstop and not proposing realistic alternatives in fact support reestablishing a border. Even if they do not admit it.
— Charles Michel (@eucopresident) August 20, 2019
Speaking on The Pat Kenny Show, Minister McEntee said Boris Johnson hasn't brought forward any concrete proposals to replace the backstop.
She observed: "There's nothing that has been suggested by the Prime Minister there that would actually address any of the concerns that we have.
"I think it's important to say that any suggestion that the backstop is being forced upon [the UK] or something that was decided solely by the EU and Ireland... is simply not the truth."
While Boris Johnson has called for unspecified "alternative arrangements", Minister McEntee said some of those alternatives have been considered.
She explained: "Any suggestions that we can have some sort of trusted trader scheme... that we can have a technological solution... again, they simply don't work.
"They have been looked at over the past three years by both the UK and the EU. In the absence of knowing what kind of future relationship we'll have - one that we hope will be close - the backstop is the one way that we can deal with all of these commitments that have been made."
She said Ireland is always ready to engage with the UK - but not in terms of a bilateral agreement.
Minister McEntee insisted: "This is something that has to be agreed between the UK and the EU, and [Ireland] as a member of the European Union.
"Of course we are not leaving, and we cannot allow a situation where a decision by another country will take us out of the EU, the single market or the customs union."
Meanwhile, EU Agriculture Commissioner Phil Hogan has suggested other Brexit proposals could be considered if the UK reconsiders their 'red lines'.
Speaking in Carlingford at the Thomas D'Arcy McGee Summer School, Mr Hogan argued: "We have to see what we can do to help the UK off the hook that they've created for themselves.
"From the word go, all the red lines [were from the UK] - no single market, no customs union, no regulatory alignment.
"We are where we are because of all the red lines from the United Kingdom - and if they change their red lines, we'll change our position."