Mr Rajoy, who is fighting to resolve the Catalonian independence crisis at home, sent a message of support to his French counterpart.
The Spanish PM, who has rejected Catalan leader Carles Puigdemont’s calls for dialogue until he comes back within the law, has kept a low profile throughout the EU summit in Brussels.
But he voiced his support for Mr Macron whose pro-European stance forms the backbone of the EU’s agenda for 2018-2019 to be put forward by European Council President Donald Tusk today.
It include closer military cooperation, tightening of the eurozone, imposing more rigid screening of foreign investments and tougher anti-dumping duties.
Rules on workers posted outside their home country are set to be overhauled and they also want to create a new system of political conventions and transnational lists in European elections.
Mr Rajoy, who held private talks with Mr Macron on the summit’s sidelines, said: “I share with Emmanuel Macron the conviction that we need to push for the integration of the get project that unites us: the European Union.”
Leaders across the bloc are being encouraged to get behind the reforms but not every member state is happy with the plans.
The Visegrad Group of ex-communist eastern European countries, who all joined the EU in 2004, have been alarmed by calls for faster and deeper integration, demands they take in refugees and possible restrictions on the right of their citizens to work in wealthier EU states.
Mr Rajoy backed the French President as Mr Macron supported Spain’s attempts to keep the country unified.
Asked if he backed the Spanish government, Mr Macron replied: “Always.”
And he said: “This summit will be marked by a message of unity of its members in regards to Spain.”
Brussels said it will not recognise Catalonia if it splits from Spain and that it would no longer be a member of the bloc.
The Spanish PM, who has rejected Catalan leader Carles Puigdemont’s calls for dialogue until he comes back within the law, said nothing as he arrived in Brussels and kept a low profile throughout the summit.
But he later tweeted: “I share with Emmanuel Macron the conviction that we need to push for the integration of the great project that unites us: the European Union.”
German Chancellor Angela Merkel said: “We’re looking at this very closely and support the position of the Spanish government, which is also a position that’s been adopted across parties.
“Of course this preoccupies us, and we hope that there can be a resolution on the basis of the Spanish constitution.”
Mr Rajoy is set to suspend Catalonia’s autonomy and impose direct rule after Mr Puigdemont threatened to issue a formal declaration of independence if Madrid refuses to hold talks.
Brussels bosses sought to minimise the crisis, describing Barcelona’s secession bid as a domestic issue and declining a mediation role.
European Council President Donald Tusk said: “It is not on our agenda.
“All of us have our own emotions, opinions, assessments but formally speaking there is no space for an EU intervention.”