Appiah's comments follow the striker's missed spot-kick in the 2-1 friendly defeat to the USA over the weekend.
Incidentally, Saturday's kick is the frontman's first penalty since deciding against taking to the spot on national duty following a backlash for missing one in a semi-final reversal to Zambia at the 2012 Africa Cup of Nations.
“Every player in the world can miss a penalty,” Appiah said.
“The good thing is that Gyan used to take our penalties and for one reason or another, he decided not to take any more for us.
“Now, he has the right to change his mind and he did so to help our nation.
“I do not believe he went there to miss the kick.
“It takes guts to take a penalty, so Gyan needs to be encouraged so he can take more penalties for us in the future.”
Gyan's penalty retirement was rooted in public uproar following some crucial misses.
At the 2010 Fifa World Cup in South Africa, the Al Ahli striker spurned a last-gasp penalty against Uruguay which could have made Ghana the first African team to reach the semi-finals of the global showpiece.
And after the 2012 disappointment, he announced his decision to stay away from penalty duties.
On Saturday, Gyan did make up for his penalty miss, scoring a sumptuous free-kick to register Ghana's consolation.