Minister for Foreign Affairs Simon Coveney has said there is a need to dial down the language between the EU and UK in the Brexit talks.
In an interview with Sky News, Mr Coveney also criticised the British government's Internal Market Bill which would allow ministers to break international law.
"The EU has said that it will have to take legal action against the UK if they proceed with breaking international law," he said.
Mr Coveney added that a Brexit deal was "very difficult but very doable" and big progress had to be made in talks this week.
"We are running out of time now," Mr Coveney said.
"Even if we do get a new trade deal negotiated by both sides, if the British government is determined to continue with their Internal Market Bill - to reintroduce parts of that Bill that were removed by the House of Lords this week - then, I think this is a deal that won't be ratified by the EU," the minister said.
"Because there is no way the EU will agree to ratify a new agreement if the British government is breaking the existing agreement that is not even 12 months old, and breaking international law by doing that."
Mr Coveney called for a cooling of rhetoric in trade talks, especially in the contentious area of fishing rights.
"We really have to try and find a way of coming up with a compromise on fish that both sides can live with," he said. "And we need to try and dial down the language on this because it is very easy to become emotive."
Mr Coveney also said top level departures from Downing Street this week have been huge distractions as the UK and EU try to finalise a future trade deal.
"I think there, of course, have been huge distractions in Number 10 this week. "But, they are not distractions for the EU. We have never focused on the personalities when it comes to Brexit."
Also speaking on Sky News, Britain's Environment Secretary George Eustice said the exit of British Prime Minister Boris Johnson's senior adviser Dominic Cummings will have no impact on crucial Brexit negotiations.
Mr Eustice said next week is "a week when things need to move" for the UK and EU to agree to a trade deal.
He said: "Both sides recognise that time is very, very short. It's not long ago we were saying we needed to get some kind of conclusion by the middle of October.
"People have persevered with these talks. There does come a point frankly where businesses need to know what they are preparing for."
Independent TD Verona Murphy, former president of the Irish Road Haulage Association, told RTE's The Week In Politics that Ireland's supply routes "will collapse" due to what she said was the Government's "failure to deal with the British land-bridge problems and ferry alternatives".
Ind TD @VeronaMurphyInd says when it comes to getting Irish produce off the Island of Ireland with the land bridge "no preparation" is being made. Rebroadcast tonight at 2200 on @rtenews and at 2300 on @rteone #rtepolitics #brexit #trade pic.twitter.com/wZF7CWCrtk— The Week in Politics (@rtetwip) November 15, 2020
Minister of State Damien English replied that this was "simply not true".
Meanwhile, as the UK's chief negotiator David Frost arrived in Brussels for talks, he said Britain will not change its stance as it seeks a post-Brexit deal with the EU.
"We are working to get a deal, but the only one that's possible is one that is compatible with our sovereignty and takes back control of our laws, our trade, and our waters. That has been our consistent position from the start and I will not be changing it," he tweeted.
2/4 We are working to get a deal, but the only one that's possible is one that is compatible with our sovereignty and takes back control of our laws, our trade, and our waters. That has been our consistent position from the start and I will not be changing it.— David Frost (@DavidGHFrost) November 15, 2020
Mr Frost said he and his EU counterpart Michel Barnier would resume their face-to-face negotiations today.
Talks over the next few days are seen as crucial for any deal before time runs out at the end of the year, when the post-Brexit transition period ends.
Mr Frost warned "we may not succeed". He noted some progress, but said "significant elements" remained to be resolved.
The persistent differences are over EU demands for a level playing field in trade to ensure fair competition and for a robust disputes mechanism, and both sides are arguing over fishing rights in British waters.