Chancellor Angela Merkel's office called the cathedral a "symbol of France and of our European culture".
"These horrible images of Notre-Dame on fire are painful," Merkel's spokesman Steffen Seibert said on Twitter.
"Notre-Dame is a symbol of France and of our European culture. Our thoughts are with our French friends."
Es tut weh, diese schrecklichen Bilder der brennenden #NotreDame zu sehen. #NotreDame ist ein Symbol Frankreichs und unserer europäischen Kultur. Mit unseren Gedanken sind wir bei den französischen Freunden. #Paris
— Steffen Seibert (@RegSprecher) April 15, 2019
The blaze swept through the building, causing the iconic spire to collapse in scenes that shocked the world.
The fire started in the attic of the historic Cathedral at around 6.50pm, and within minutes images and videos of the blaze were being shared around the world.
The cause of the blaze has not been confirmed but the 850-year-old cathedral had been undergoing intense restoration work.
Built between the years 1163 and 1345, Notre-Dame is one of the most popular tourist sites in Paris, drawing around 13 million people every year.
Germany's Foreign Minister Heiko Maas also commented on the fire. He said it "hits us in the heart".
"Our thoughts are with all the emergency services and our French friends." Maas added that he hoped no one was hurt in the blaze.
Die brennende #NotreDame trifft auch uns ins Herz. Unsere Gedanken sind bei allen Einsatzkräften und unseren französischen Freundinnen und Freunden. Wir hoffen gemeinsam mit ihnen, dass bei dem Brand keine Menschen zu Schaden kommen.
— Heiko Maas (@HeikoMaas) April 15, 2019
People pray at the sight of Notre-Dame burning. Photo: DPA
Andrea Nahles, leader of the centre-left Social Democracts (SPD) said seeing the cathedral in flames was a "terrible sight". She praised the firefighters "who are trying to save the Parisian landmark".
"A tragic day for our French friends, we are with them," she added.
#NotreDame in Flammen – ein furchtbarer Anblick! Alles Gute den Feuerwehrleuten, die das Pariser Wahrzeichen zu retten versuchen! Ein tragischer Tag für unsere französischen Freunde, wir fühlen mit ihnen.
— Andrea Nahles (@AndreaNahlesSPD) April 15, 2019
Greens co-leader Annalena Baerbock also spoke of her sadness. She wrote in French that her heart was with Paris and added: "With Notre-Dame, a part of our European history is burning at this moment. How incredibly sad."
Leader of the pro-business Free Democrats said: "To all the French: we weep with you."
— Christian Lindner (@c_lindner) Read More – Source