Italy's new President Sergio Mattarella (R) receives a decoration from his predecessor Sergio Napolitano at the Qurinale presidential palace in Rome in this February 3, 2015 handout photo by the Italian Presidency Press Office. [Photo/Agencies]

ROME -- Sergio Mattarella, the new Italian president, started his seven-year mandate on Tuesday with a promise to guarantee the rule of law amid high appreciation of the local political and social world.

In his 35-minute inaugural address interrupted by applause for more than 40 times, which followed the swearing-in at the lower chamber, 73-year-old Mattarella, a former constitutional judge, stressed his will to be an "impartial referee."

His predecessor Giorgio Napolitano, who resigned last month before the end of the second tenure, defined Mattarella's words as "essential and not rhetorical."

Mattarella called on politicians to be transparent and coherent in their decisions. Right to education and work, and fight against crime and terrorism were among the main topics addressed in his speech.

"Mattarella's words seemed to me adequate, respectful of the Constitution," said three-time prime minister Silvio Berlusconi, whose lawmakers belonging to his center-right Forza Italia (FI) party, a major opposition force in parliament, mainly cast blank ballots.

Even the anti-establishment Five-Star Movement (M5S), which had voted another candidate - senior magistrate Ferdinando Imposimato - promoted Mattarella. "For the moment he is promoted, but we are awaiting his action," M5S lawmaker Roberto Fico said.