Dortmund emerged as Group F victors in the Champions League and now face a last-16 clash against Zenit St Petersburg, while Germany will be among the favourites in Brazil later this year.
And, when asked by Bild whether he would prefer to be crowned club champions of Europe or World Cup winners, midfielder Reus remarked: "Both.
"These are two very big goals and both are not entirely misguided.
"(In the World Cup) We have to perform from the beginning on the pitch. We will prepare meticulously and hard for this super tournament."
And the 24-year-old dismissed some claims that Dortmund had been dealt an easy draw in the Champions League.
"Many say we have a simple draw in Zenit," he continued. "But they are a really good team, have a super striker Hulk, and it will be really cold in St. Petersburg."
Dortmund have been well off the pace in the Bundesliga this season and currently sit 12 points behind leaders Bayern Munich in fourth.
While admitting that Bayern are the best team in Europe at present, Reus vowed that Dortmund would soon turn the corner and challenge Pep Guardiola's men.
"I promise, we will attack again," he stressed. "Bayen is currently the best team in Europe, but it will serve as an incentive for us to be even better."
With regards to his future, Reus reassured Dortmund fans: "I have a valid contract with BVB and am happy to be here."
