Goetze came off the substitutes bench to score a stunning 113th-minute goal as Germany beat Argentina 1-0 at Rio de Janeiro's Maracana Stadium. (Agencies)
"I told Mario Goetze, 'go out and show the world you are better than Messi'," said Loew.
"Goetze is the miracle boy, he is the wonder who can play in numerous positions, he is the decider who can come on and make a difference and that is what he did today,” he added.
The German coach meanwhile basked in his team's historic win, the first by a European team in South America.
It came after four consecutive near-misses in major tournaments stretching back to 2006.
"We have been together for 55 days, we have started this project years ago and this is the culmination of a lot of hard work," Loew said.
"We have been able to improve our performances, we believed in it and worked a lot for it. This team really deserves it with the likes of Philipp Lahm, Bastian Schweinsteiger, Lukas Podolski and Per Mertesacker,” he added.
"We have had disappointment in the past having gone close despite playing good football. I think we put in the best performances over all the seven matches of all the teams here,” he said.
Loew said the tournament triumph was forged on team spirit.
"This team has developed an unbelievable team spirit and has developed a marvellous mental capacity," he said.
"And we are proud to become the first European country to win the title in South America. In Brazil, In Rio is this football-loving country and that makes us very proud,” he added.
"This deep joy and happiness will last forever, the team gave all they had lead by the marvellous Bastian Schweinsteiger in midfield and Philipp Lahm, who ran a number of kilometers,” he said.
Loew added, “I told the team before kick-off that they would have to give more than they had ever given before, because they wanted to achieve something we had never previously achieved.”
Loew said one of the highlights of his career had been Germany's 7-1 semi-final hammering of hosts Brazil last Tuesday but the reaction of the host country's football-crazy supporters had taken him by surprise.
"It is one of the highlights of my career that after we beat Brazil, although the disappointment was enormous, the Brazilians applauded us," said Loew.
"The drive took an hour to the airport, but we had Brazilians cheering us on the sidewalks. When we were about 10 minutes from our World Cup base in Bahia, we saw people welcoming us with flags and banners and that really got under our skin,” he added.
"I told the team we are going to a foreign country and we are representing 80 million Germans but I wanted the local people to feel that the team were focused on their football, but enjoying themselves. The people supported us with joy and love and I want to say 'Thank You, Brazil',” he said.
Loew also praised his side for nullifying the threat of Argentina's superstar Lionel Messi, who was voted player of the tournament but failed to breach the German defence.
"Both teams had their chances, but we had the better part of the game and possession," said Loew.
"In extra-time, we had the sufficient energy, we didn't want penalties and we wanted to decide the match before. Argentina had the mind to wait and then counter-attack, when they got the ball, players like Messi were fed possession up front,” he added.
"We had players who went straight to Messi as soon as he got the ball and it meant he was never able to get running, we did that a couple of times and it worked well,” he further said.
Goetze came off the substitutes bench to score a stunning 113th-minute goal as Germany beat Argentina 1-0 at Rio de Janeiro's Maracana Stadium.