Sacked Catalan leader Carles Puigdemont has called for “democratic opposition” to direct rule from Madrid.
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 pre-recorded TV address to Catalans broadcast on Saturday afternoon.
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.
And Spain’s interior ministry has taken 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 order fresh regional elections in December.
An official state bulletin (in Spanish) handed control of Catalonia to Spain’s Deputy Prime Minister, Soraya Saenz de Santamaria.
Demonstrations for and against independence went on into the night, and a large rally “for the unity of Spain and the constitution” was held in Madrid on Saturday.
In his TV address, Mr Puigdemont, describing the declaration of independence, said Friday had been “a day with democratic and civic sensibility”.
He said the central government’s actions since then were “premeditated aggression” that ran “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”.
He added: “We continue persevering in the only attitude that can make us winners. Without violence, without insults, in an inclusive way, respecting people and symbols, opinions, and also respecting the protests of the Catalans who do not agree with what has decided the parliamentary majority”
The crisis was sparked by an independence referendum organised by the Catalan government and held earlier this month 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.