"When a new spirit began to sweep through Eastern Europe in the 1980s, when freedom was won in Poland, when fearless people in Leipzig, East Berlin and elsewhere in East Germany staged a peaceful revolution, Helmut Kohl was the right person at the right time", said Merkel.
Diplomatic relations between Germany and the United States were at an all-time high at the time when Kohl led his country.
Kohl left active politics in 2002.
Mattarella wrote to German President Frank-Walter Steinmeier saying "I have learned with deep sorrow of the passing of Helmut Kohl, a political personality of extraordinary significance in the recent history of Germany and the whole of Europe". He has served as the Chancellor of West Germany from 1982 to 1990 and reunited Germany from 1990 to 1998.
Kohl died on Friday at his home in Ludwigshafen, in southwestern Germany. He was previously married to Hannelore Renner in 1960, who committed suicide due to an unbearable medical condition. Often harsh and thin-skinned, Kohl also could display a quick wit and jovial earthiness. Kohl decided this - without consultation with the Bundesbank, the hitherto all-powerful German central bank - in February 1990 in the helter-skelter aftermath of the fall of the Berlin wall the previous November. In 1988, Kohl and former French president François Mitterrand received the Charlemagne Prize.
Kohl lobbied heavily for the introduction of Euro, which was implemented in 1999 and went on to become a currency that now unites 19 countries in Europe, BBC reported.
"Helmut Kohl filled the European house with life - not only because he built bridges to the west as well as to the east, but also because he never ceased to design even better blueprints for the future of Europe", Juncker said.