"We have listened to the world, especially Europe, and I think it would be very good if the Spanish Government also was generous and responsible and listened that this is the moment and the opportunity to open a dialogue without conditions". "Some aspects of territorial coexistence must be updated", he said, announcing that he had reached an agreement with Rajoy to reform the Spanish constitution.
The government stuck to its stance said that it would not accept mediation or any talks until Catalan leaders drop their Independence bid.
Spain has been in turmoil since a disputed referendum in Catalonia on October 1 was declared invalid by the country's Constitutional Court.
Mr Rajoy has vowed to use everything in his power to prevent independence and has refused to rule out imposing direct rule over the semi-autonomous region - an unprecedented move many fear could lead to unrest.
He said: "This call - ahead of any of the measures that the government may adopt under Article 155 of our constitution - seeks to offer citizens the clarity and security that a question of such importance requires".
Spain Prime Minister Mariano Rajoy was due to hold an emergency cabinet meeting on Wednesday to discuss the government's next steps.
"There is an urgent need to put an end to the situation that Catalonia is going through - to return it to safety, tranquillity and calm and to do that as quickly as possible".
On the same day that Catalonia's president called for negotiations with Spain to secure independence for his state, the White House signaled it favored talks between Catalonia and the Madrid government and "them moving forward". Italy does not recognize Catalonia's unilaterally proclaimed independence and believes that Spain's territorial integrity must be preserved, Italian Foreign Minister Angelino Alfano said on Tuesday evening.
The move came after the October 1 independence referendum in which 90 per cent of participants voted in favour of splitting from Spain. Spanish police cracked down on the polls, beating some voters as they closed down polling stations.
If Puigdemont was to confirm he did declare independence, he would be given an additional three days to rectify.
Catalonia's separatist camp has grown in recent years, strengthened by Spain's recent economic crisis and by Madrid's rejection of attempts to increase self-rule in the region.