Kwesi Appiah's men were beaten 2-1 on Monday thanks to a late goal from John Brooks as Ghana lost arguably their most winnable game of the group.
With fixtures against Germany and Portugal to come, Gyan expressed Ghana's need to refocus for the fixture against Joachim Low's men.
The free-scoring German side put four past Portugal in their opener but the Al Ain striker said there was no time to dwell on the defeat.
"We have to improve in the remaining games and that’s the target," he said.
"The defeat to the US is painful but we do not have time to lament. We have to focus on our game against the Germans."
‘I had to prove myself to the Nottingham Forest fans after crossing the divide from Derby, but it didn’t take too long – I showed I was there to score goals’: Ex-Forest striker reveals how tough start at City Ground quickly changed
The games Arsenal star Bukayo Saka is expected to miss following his painful injury setback
