The 32-year-old Bayern Munich star is one of four goalkeepers named by head coach Joachim Loew, who will have to cut four names when the final 23-man squad is submitted for the World Cup finals, which start on June 14 in Russian Federation. Loew opts for Petersen over Bayern Munich forward Sandro Wagner.
"Manuel is getting back into full training this week at Bayern Munich, that assures us that he can tolerate the full load in the training camp", explained Loew.
"We've been in constant contact with Manuel".
The title-holders will have to submit their final 23-man squad including three goalkeepers on June 4.
Petersen helped his club stay in the Bundesliga with 15 goals in 32 league appearances, eight of those as a substitute.
Goetze scored the winning goal in the 2014 World Cup final.
"Marco is a special weapon, he has special gifts", Loew said.
"It wasn't his best season".
Midfielders: Julian Brandt (Bayer Leverkusen), Julian Draxler (Paris Saint-Germain), Leon Goretzka (Schalke), Ilkay Gundogan (Manchester City), Sami Khedira (Juventus), Toni Kroos (Real Madrid), Mesut Oezil (Arsenal), Sebastian Rudy (Bayern Munich).
Grindel struck a more conciliatory note on Tuesday, saying, "People can make mistakes and we have to keep things in perspective. The federation made me understand that they wanted me 100 percent and that made it easy for me to choose", added the former Inter Milan, Manchester City, Galatasaray and Zenit St Petersburg coach.
Germany will start their World Cup campaign on 17 June, with Mexico, Sweden and South Korea in their group F. "Some (of the reaction) seems to be over the top to me".