The “voice of the Scottish people” will not be silenced, Nicola Sturgeon has told independence supporters after the UK’s highest court ruled Holyrood could not legislate for a referendum.

The Supreme Court announced a unanimous decision on Wednesday stating the Scottish Parliament did not have the necessary powers to hold a vote on separation.

But the First Minister struck an upbeat tone during a rally outside the parliament on Wednesday, as she said the UK was “not a voluntary partnership of nations”.

“Any partnership in any walk of life that requires one party to seek the consent of another to choose its own future is not voluntary – it is not a partnership at all,” she said.

“And while today’s ruling may create temporary relief on the part of unionist politicians and parties, they should know the hardest questions that have been posed today are questions for them.”

The First Minister added: “The Westminster establishment may think they can block a referendum, but let me be clear… no establishment, Westminster or otherwise, will ever silence the voice of the Scottish people.”

The SNP leader added that “our job as Scotland’s peaceful, civic, inclusive, internationalist independence movement is the same today as it was yesterday”.

She ended her speech, telling the hundreds gathered outside Holyrood: “Let’s get to it, my friends, let’s win our independence and build the Scotland we know is possible.”

SNP MP Tommy Sheppard told the crowd they were protesting to “assert and defend” their right to self-determination “and to say we will not submit, we will not give up, we will not give up our campaign for our independence”.

“The right to choose, the need to choose has never been more essential,” he said.

“You only have to look at what is happening in the United Kingdom at the moment – a government of spivs and millionaires that are recklessly engaged in a right-wing economic experiment that has brought misery and reduced the living standards of millions of ordinary people.”

The MP for Edinburgh East, who is also the party’s spokesman on constitutional affairs, described the court verdict as a “set back” but told protesters they should not be disheartened.

“We know now what we need to do. If the British state will not allow a democratic event such as a referendum to be able to express the will of the people, then we will find other means to allow the people to have their voice,” he said.