The Italy forward entered the Brazil showpiece on the back of a prolific campaign with Torino in Serie A, netting 22 goals to top the scoring charts.
That led to a big-money switch to the Bundesliga, but the 24-year-old did not impress at the World Cup, failing to score in both matches he played as Cesare Prandelli's side were knocked out in the group stages.
Watzke has leapt to Immobile's defence, though, and is adamant he will be a hit with Dortmund fans in the absence of Robert Lewandowski, who made the switch to German champions Bayern Munich.
"Ciro didn't have one game at the World Cup in which he could really prove himself," Watzke told Sport Bild.
"The Italians should be happy that they've got such a great player for the years to come rather than making him responsible for everything.
"As soon as he arrives here, he's not going to think about the World Cup even for a second.
"We're all looking forward to him arriving."
In addition to Immobile, Dortmund have further bolstered their attacking options with the signings of Adrian Ramos and Ji Dong-Won.
