Comments from UK ministers on Brexit are "gravely concerning", Irish Foreign Minister, Simon Coveney, said.
The minister added that any departure from the rule of law would have "serious complications for the UK's international reputation."
Coveney also said that the Northern Ireland protocol must be implemented by the end of the year when the transition period expires.
"There will be no appeasing of this approach and there will be no condoning of a strategy that proposes to breach international law to undermine an agreement," Coveney also said, as quoted by Reuters.
According to him, UK's approach is "hugely problematic and illegal", however, Ireland "must focus on how to get an agreement."
Coveney's statements came shortly after Johnson's spokesman said earlier in the day that the UK government would prevent any "damaging" scenario from happening in case London and Brussels were unable to agree upon the details of the withdrawal agreement and Northern Irish protocol.
Prior to that, reports emerged that Johnson was seeking to override some parts of the withdrawal agreement, in areas dealing with state aid and the Northern Ireland Protocol, designed to prevent a hard border and customs checks in Ireland.