European Union leaders have stressed they are not seeking a “political victory” over the UK as they pushed back sharply against demands that the Northern Ireland Brexit protocol be scrapped.

After a two-day trip to Northern Ireland, the European Commission vice-president, Maroš Šefčovič, repeated his warning that a renegotiation would merely lead to more instability for businesses and communities.

“I will not mince my words. The protocol is not the problem. On the contrary, it is the only solution we have. Failing to apply it will not make problems disappear, but simply take away the tools to solve them,” he said.

Just hours after the Democratic Unionist party had threatened to collapse the Stormont assembly with elections nine months earlier than scheduled, Šefčovič said he had listened to the leaders of all parties and was “ready to explore all the flexibilities” being proposed but renegotiation was a non-starter.

“I do not need any political victory here. I want to find a solution that represents win-win, first of all for the people of Northern Ireland.

“I believe that if there is a good deal and a good cooperation, we can we can achieve it,” he said. “Can we do this [negotiation] faster? Let’s go for it,” he said.

But he urged politicians to “dial down the rhetoric” and give both sides calm space to work to ease tensions.

Under the protocol, designed to avoid a hard border on the island of Ireland, Northern Ireland observes EU rules on goods coming in from Great Britain, requiring businesses ranging from supermarkets to car parts suppliers to provide customs and other paperwork when taking goods across the Irish Sea.

Speaking to an audience at Queen’s University in Belfast, Šefčovič said he was “acutely” aware of the unionist unease with the protocol but that there was no alternative, given Boris Johnson’s government had opted for a hard Brexit.

“While we will continue looking for solutions to minimise the effects of Brexit on your everyday lives, we will never be able to remove them entirely – such are the consequences of Brexit and of the choices of the UK government,” he said.

“Renegotiation of the protocol – as the UK government is suggesting – would mean instability, uncertainty and unpredictability in Northern Ireland. Bear in mind it has already taken us five years to get to this point.”

He was speaking just days after the Brexit minister, David Frost, said the UK preferred to keep the protocol but only if there were substantial changes with regards to the controversial checks on goods traded across the Irish Sea.

Šefčovič and Frost are the chief interlocutors in the continuing dispute over the protocol, agreed in a meeting with the then Irish prime minister, Leo Varadkar, at a hotel in Wirral in 2019.

But the protocol has caused deep unease in the unionist and loyalist communities who think that the checks on goods coming in from Great Britain are an assault on Northern Ireland’s place in the UK.

Šefčovič told reporters he had met the DUP leader, Jeffrey Donaldson, “a couple of weeks ago” and found him to be “a very experienced politician”. But he said he shared Donaldson’s desire to achieve what’s best for Northern Ireland. “I can assure him that is my intention as well,” he said.

“I am, of course, acutely aware of how some in Northern Ireland feel about the protocol, in particular in the unionist community,” he told the audience at Queen’s.