The suspension order has inflamed one of the biggest political crises to hit Spain in decades. The court said it had agreed to consider a legal challenge filed by the anti-secessionist Catalan Socialist Party.
The speaker of Catalan’s parliament blasted back that the constitutional court’s ruling harms freedom of expression.
Carme Forcadell said the parliament had taken no decision yet on whether Monday’s session would go ahead.
She said: “The court’s decision to suspend Monday’s session before it had been formally convened “harms freedom of expression and the right of initiative of members of this parliament and shows once more how the courts are being used to solve political problems.”
Last week’s referendum was banned by Madrid and marked by violent scenes at electoral stations where Spanish police sought to hinder voting.
Prime Minister Mariano Rajoy called on Catalan leader Carles Puigdemont on Thursday to abandon plans to unilaterally declare independence from Spain or risk “greater evils”.
In an interview with Spanish news agency EFE, Mr Rajoy said the solution to the Catalan crisis was a prompt return to legality and “a statement as soon as possible that there will not be a unilateral declaration of independence, because that will also avoid greater evils.”
He did not elaborate but ruling party lawmakers say that Mr Rajoy, a conservative who has taken a hard line on Catalan independence, is considering the unprecedented step of dissolving the Catalan parliament and triggering regional elections.
Catalan officials released preliminary referendum results showing 90 percent support in favour of breaking away.
But turnout was only about 43 percent as Catalans who favour remaining part of Spain mainly boycotted the ballot and many polling stations were closed.
Mr Puigdemont said he was not afraid of being arrested for organising Sunday’s banned referendum.
He told Bild: “Personally, I am not afraid of that. And I’m not surprised any more about what the Spanish government is doing. My arrest is also possible, which would be a barbaric step.”
Neither the Spanish government nor the judiciary has threatened to arrest Mr Puigdemont, though Madrid accuses him of breaking the law by ignoring a Constitutional Court ruling forbidding the referendum from going ahead.
On Wednesday, in a televised address, Mr Puigdemont renewed his call for international mediation but said the results of the referendum would have to be applied.
He has not explained the scope of his proposal for international mediation, whether it would envisage a compromise short of independence or deal only with divorce arrangements.
Mr Rajoy has ruled out international mediation as a format for resolving the future of Catalonia, offering instead all-party Spanish political talks to find a solution, on the condition independence is taken off the table.
Sunday’s crackdown by Spanish police, Mr Rajoy’s hardline stance and an uncharacteristically strong intervention this week by Spain’s King Felipe VI seems to have deepened Catalonia’s resolve to continue with the project.
Mr Puigdemont told Bild: “We will go as far as people want it. But without the use of force. We were always a peaceful movement. And I am sure that Spain will not be able to ignore the will of so many people.”