Meanwhile, the regional president of Catalonia, Carles Puigdemont, announced he would appear in the regional parliament on Tuesday to explain the political situation.
The Catalan government on Friday said approximately 90 percent of those who voted opted for independence, although turnout was only 43 percent.
"We will show these minoritarian secessionists that Spain is a modern country", Nobel Literature Prize victor Mario Vargas Llosa said in a speech at the end of the rally. "We are facing a tremendous unknown".
The Minister believes that the crisis should be resolved through dialogue at all levels of Spanish politics.
The minister also reiterated Brussels' warning that an independent Catalonia would "automatically" be out of the European Union and have to reapply to join.
Tempers have worsened over the past week after national police cracked down on voters during a banned October 1 Catalan independence referendum.
In Barcelona, protesters chanted "let's talk" in Catalan, while many carried signs criticising political leaders for not finding a diplomatic solution to the impasse. "As a matter of global law, the disproportionate use of force is not lawful, and what happened on the streets of Catalonia was not lawful".
Many Catalans have long highlighted the region's differences from the rest of Spain but the latest surge for independence began in 2010, when Spain's top court struck down key parts of a charter that would have granted Catalonia greater autonomy and recognized it as a nation within Spain.
Meanwhile, Spanish Prime Minister Mariano Rajoy has emphatically ruled out negotiating with the Catalan government ahead of its declaration of independence scheduled for October 10.
The Spanish government will try to cause the "least possible damage" in connection with Catalonia's unilateral decision on independence, but will act to restore law in the region.
According to Spanish media, a sentence where Puigdemont added that "the declaration of independence is planned in the referendum law" and he "will apply what is planned in the law" was cut in the final version of the interview.
Tensions have grown in Spain since last week when Catalonia held a regional vote for independence, an election deemed illegal by Madrid.
Catalonian officials claim the referendum results give them a mandate to create a new country.
The region, home to 7.5 million people with their own language and cultural traditions, accounts for a fifth of Spain's economy.