Democratic Unionist Party (DUP) leader Arlene Foster has said Sinn Féin must choose between making a deal with them or having direct rule ministers in place.
Speaking at the party’s annual conference, she said “time is short”.
Mrs Foster also spoke of the DUP’s influence in Westminster and the party’s commitment to Brexit.
DUP MPs are propping up the Conservative government as part of a confidence-and-supply deal.
On the failure of talks between the DUP and Sinn Féin, Mrs Foster said that “some progress was made but that can only be built upon if all sides are genuinely serious about obtaining a deal that is balanced”.
The DUP-Sinn Féin power-sharing government fell apart in January following a row over a green energy scandal, which is now the subject of a public inquiry.
A series of talks have failed to find agreement over issues including an Irish language act and same-sex marriage.
“I said back in the summer that this party was prepared to legislate for the Irish language in the context of legislating for the plurality of cultures that exist in Northern Ireland,” Mrs Foster told the conference in Belfast.
“The Irish language is spoken and enjoyed by thousands of people in all parts of Northern Ireland, it does no damage to our unionism or the Union we cherish.
“I respect the Irish language and those who speak it, however, respect isn’t a one-way street.
“Respect works both ways.”
Mrs Foster said Sinn Féin needed to “respect our British culture”.
“For too long they have shown nothing but disdain and disrespect for the national flag, the Royal Family, the Armed Forces, British symbols, the constitutional reality and the very name of this country.
“Time is short and those in Sinn Féin blocking the restoration of local decision making need to decide whether they want to do business with us or have direct rule ministers in place.
“I still believe that devolution is the best way to govern Northern Ireland, but to do that in a way that delivers for all of our people we need serious partners in government.”
On Brexit, Mrs Foster said it was “perhaps the most substantial and complex process the government and parliament had undertaken in the modern political era”.
She reiterated her desire to find a solution for Northern Ireland that would not harm the country’s economic relationship with either the rest of the UK or the Republic of Ireland.
“As we joined the then European Community as one nation we will leave as one United Kingdom,” she said.
Responding to Mrs Foster’s address, Sinn Féin’s northern leader, Michelle O’Neill said she and her party “remained committed to making the institutions work,” but said: “They must operate on the basis agreed 20 years ago.”
“A majority of citizens in the north expect and are entitled to the same rights enjoyed by citizens across these islands; language and marriage equality rights, due process in all aspects of the legal and judicial system, including inquests.”
Earlier, the party’s deputy leader Nigel Dodds told the conference that the deal with the Conservative Party was “in the national interest” and an opportunity for Northern Ireland.
“Our interests in the negotiations were not in seats for ourselves at the cabinet table but in jobs and investment for our people,” he said.
“Our goal is not to push some narrow DUP agenda but to deliver for the whole community in Northern Ireland,” he added.
The Conservative Party are represented at the conference through senior minister Damian Green and chief whip Julian Smith, who is due to give a keynote speech on Saturday afternoon.
Mr Dodds also addressed the ongoing political deadlock at Stormont.
Mr Dodds said Northern Ireland Secretary James Brokenshire must soon consider implementing direct rule if no deal is struck.
“While we understand, because of the talks process and the absence of ministers, things have been more difficult, within a very short space of time that will not be a tenable excuse for not taking action,” he said.
“None of us want to see direct rule introduced but we are fast approaching the moment when it will be the lesser of two evils.”