The midfielder played no part in Germany's World Cup success after suffering an ankle ligament injury, but made his return in Saturday's 4-1 DFB-Pokal first-round win at Stuttgarter Kickers.
Henrikh Mkhitaryan, Adrian Ramos and a double from Pierre-Emerick Aubameyang settled the match in favour of the visitors - who also welcomed back defender Neven Subotic following a nine-month absence due to a knee injury.
Klopp was happy to see Reus back in action, but knows he must be patient with the former Borussia Monchengladbach man.
He said: "I am very satisfied with Marco. The fact that he could not show his absolutely outstanding quality is not a problem for me.
"Marco has everything ready. He has trained for two weeks, is fit and in top form. We'll see how it [his return] goes, [but] we won't take risks."
Third-tier outfit Stuttgarter put up a good fight and looked threatening for long stretches at the Mercedes-Benz Arena, with Klopp acknowledging that the result flattered Dortmund.
"The result is dramatically better than what has happened on the pitch. But the Bundesliga season starts next week. Now we are again a bit further [along in terms of fitness] and fresh."