Sacked Catalan leader Carles Puigdemont has called for “democratic opposition” to direct rule from Madrid by Spain’s government.
He condemned the suspension of Catalonia’s autonomy and promised to continue to “work to build a free country”.
He made the call in a TV address broadcast from an undisclosed location.
The Spanish government has stripped Catalonia of its autonomy and taken charge of its government.
The measures came early on Saturday after the Catalan parliament voted to declare independence the previous day.
Earlier, Spain’s interior ministry took charge of Catalonia’s police after firing senior Catalan police officials.
Friday saw Spanish Prime Minister Mariano Rajoy announce the dissolution of the regional parliament and the removal of Mr Puigdemont as Catalan leader, and call snap regional elections.
An official state bulletin handed control of Catalonia to Spain’s Deputy Prime Minister, Soraya Saenz de Santamaria.
In his TV address on Saturday, Mr Puigdemont, describing the declaration of independence, said Friday had been “a day with democratic and civic sensibility”.
He added: “The Catalan parliament fulfilled what Catalan citizens voted for on 27 September 2015.”
He was referring to the independence referendum organised by the Catalan government on that date in defiance of a ruling by the Constitutional Court which had declared it illegal.
The Catalan government said that of the 43% of potential voters who took part, 90% were in favour of independence.
Mr Puigdemont said central government’s actions since Friday were “contrary to the expressed will of the citizens of our country, who know perfectly well that in a democracy it is parliaments that choose, or remove, presidents”.