Boris Johnson has promised to end "ludicrous barriers" to trade in the Irish Sea, and says he does not see a border poll taking place for a "very, very long time".
The Prime Minister makes the comments for a BBC Spotlight special to be broadcast tonight focusing on the creation of Northern Ireland.
It follows violent clashes on the streets, with loyalists venting their anger over trade arrangements set up as a result of Brexit.
In the hour-long programme, Taoiseach Micheal Martin says tension around the protocol has become sensationalised and the voices of businesses and farmers who see benefits to the new arrangements are not being heard.
On the issue of a unity referendum, he refuses to comment on a timescale but says he did expect there to be an entirely different political dispensation on the island of Ireland in a 100 years' time.
Mr Johnson says he believes it is possible to "sandpaper" the controversial protocol into shape.
And he warns the Government would take further action if the EU insists on creating difficulties over the supply of items like British rose bushes, soil and sausages across the Irish Sea.
He says he accepts the implementation of the deal does not keep a promise to respect Northern Ireland's place in the UK's internal market.
Specifically, he says any checks on goods moving across the Irish Sea had always been intended to be light touch measures.
Unionists opposing the current arrangements have called for the protocol to be scrapped and have launched a legal challenge, arguing it breaches the Act of Union.
Mr Johnson says he will invoke Article 16, which allows the UK or EU to suspend the protocol, if he concludes the trading checks aren't fit for purpose.
Describing himself as a proud unionist, the Prime Minister says he will be happy to celebrate the centenary, but admits the last 100 years had often meant unhappy and difficult times for the nationalist people.
On the issue of a border poll, he says he doesn't believe it should take place for "a very, very long time to come", and says he prefers for the people of the UK to think of what they can do together instead of pulling apart.
In his interview, Mr Martin denies the protocol is a threat to Northern Ireland's constitutional future or that it is tearing the UK apart. The Taoiseach believes the early signs were that unionists were going to work with the protocol in a pragmatic way.
He is also asked about the Loyalist Communities Council, a group that represents loyalist terror groups, formally withdrawing its support for the Good Friday Agreement.
Despite calls from the LCC for peaceful and democratic protests, there have been reports of threats from some loyalists against Irish ministers.
Mr Martin says it is now vital for all political leaders to "ensure calm deliberation of these issues".
While stating it is his "firm belief the vast majority of people on the island have left violence well behind", he says holding a border poll too soon would be "very explosive and divisive".
The Spotlight special - A Contested Centenary - is presented by BBC NI's former political editor Mark Devenport.
It will be broadcast tonight at 9pm on BBC One NI.
The programme will also discuss the results of a major cross-border opinion poll carried out for the programme.