Spanish prosecutors said they will take legal action against Artur Mas after he went ahead with a symbolic independence referendum in defiance of a court injunction.
The head of the Catalan government held talks with other senior politicians on whether to hold early elections in the Spanish region after a symbolic weekend independence vote.
Catalonia has promoted its language and popular culture since the 1980s, cultivating a sense that it is different from the rest of Spain which has now turned to separatism.
The Spanish central government said it will challenge in court plans by Catalonia to hold a symbolic vote on whether the wealthy region should be independent.
Thousands of pro-independence Catalans rallied, demanding snap elections after the region's leader Artus Mas watered down plans for a referendum on separating from Spain.
Spanish Prime Minister Mariano Rajoy called for calm and dialogue as Catalonia leaders pressed ahead with a vote on independence in defiance of Madrid.