The Plaza de Colon was turned into a sea of Spanish flags on Saturday as some jumped into a fountain and danced.
Catalan authorities say they won Sunday's referendum by a landslide, but Spain says the vote was illegal, invalid and unconstitutional.
Less than half of the electorate cast ballots in the referendum which was marred by a brutal police crackdown.
In Barcelona, protesters dressed in white and carrying balloons filled the Placa Sant Jaume to express their support for dialogue instead of confrontation in the standoff over Catalonian independence.
People clapped, chanted and held signs including one which read "Violence no, talking yes!"
The most recent regional elections and polls taken before the referendum showed that the region's 7.5 million residents were roughly split on the divisive issue.
Catalonia's top two banks, Caixbank and Banco Sabadell, as well as energy giant Gas Natural, hurriedly transferred their headquarters to other parts of Spain this week. Other leading Catalan companies have said they are considering similar moves.
Separatist lawmakers had planned to discuss a secession plan on Monday, but that session in the regional parliament was suspended by the Constitutional Court.
The focus has now shifted to Tuesday, when Catalan president Carles Puigdemont is set to address the regional parliament "to report on the current political situation" in Catalonia.