Dressed in white and holding white balloons to signify a desire for peaceful negotiation, people on both sides of the issue urged regional and national politicians to find a peaceful way out of the crisis.
Some held handwritten signs aloft saying "Let's talk" or "The streets belong to all."
Neither Catalan nor Spanish flags could be seen at the rally, the latest in a series to be held in Barcelona, capital of the wealthy northeastern Catalonia region.
Mercè Remolí, 64, a retired journalist, told CNN the protesters were dressing in white to avoid "flags taking over the conversation."
The referendum, ruled illegal by the country's highest court, has stoked fierce divisions in Catalonia and across Spain, with neither the Catalan regional government nor the government in Madrid willing to give ground.
It remains unclear whether Catalan President Carles Puigdemont will seek to declare independence for the region next week.
Another pro-dialogue demonstrator, lab technician Antonio Gomez, 52, told CNN he was pessimistic about what might happen next.
He said Puigdemont was cornered "between the sword and the wall" because if he turns back now, those who back independence will want him out of power.
Protesters dressed in white also rallied Saturday in Madrid, calling for dialogue.
But in a sign of the simmering divisions, large numbers of people poured into Spain's capital for an anti-separatist demonstration. There, the red and yellow national flag was widely in evidence.
More demonstrations are expected through the weekend.
Faced with the prospect of an extraordinary rupture, the Spanish government is weighing its options. One is to invoke emergency powers under Article 155 of the Spanish Constitution, which allows Madrid to impose direct rule on a region if it acts outside the law.
Madrid's representative to Catalonia apologized Friday for the violence during Sunday's vote. Hundreds of people were injured then as police tried to prevent the referendum from going ahead.
In the first note of contrition by a Spanish government representative, Enric Millo told broadcaster Catalan TV3: "I insist, I'm really sorry, I want to apologize because I wouldn't wish anything like that to happen to any person, the fact that people got hit and required assistance."
In Barcelona, Catalan authorities published official results from Sunday's referendum, showing 90% voted in favor of independence and nearly 8% against, with about 2% of ballots left blank. The turnout was 43% -- nearly 2.3 million people voting out of a possible 5.3 million.
A session of the Catalan Parliament will be held Tuesday to discuss the "current political situation," a Parliament spokesman said. The Spanish Constitutional Court had banned a session of the Catalan Parliament
planned for Monday in an apparent attempt to prevent Puigdemont's expected declaration of independence.