Gyan put his side into a second-half lead with a well-taken finish after Andre Ayew had cancelled out Mario Gotze's opener, but Miroslav Klose scored a record-equalling 15th World Cup goal to rescue a point for the Europeans.
Despite surrendering their one-goal advantage, Gyan refused to be too downbeat after what he described as a "great game".
He told BBC Sport: "It was a great game and I would like to congratulate the team - we believed in ourselves against a tough side. We had to respect Germany, but we were close.
"We saw the real Ghana today. We were tactically perfect, we had to work hard because Germany are so good in possession. We didn't want to run around and waste energy.
"Now we have to go all out against Portugal in our last game. We have to focus and believe we can beat Portugal."
The USA, who beat Ghana in their first game, can now qualify for the last 16 if they win against Portugal on Sunday.