Ghana progressed to Sunday's final with a 3-0 win in Malabo, but crowd trouble forced a lengthy suspension in play before the last-four match could be completed.
Projectiles were aimed at Ghana officials and fans - who were forced onto the pitch in search of safety.
A furious Nyantakyi labelled the conduct of those responsible as "the highest state of barbarism" and condemned the lack of protection for Ghana supporters.
Nyantakyi told BBC World Service: "We're lucky we haven't lost any lives, though people have sustained injuries arising from objects thrown at them.
"African football has grown beyond this level and in the 21st century we expect to see more decency in the behaviour of fans.
"A high-profile game of this nature should have attracted police, intelligence officers and military.
"I couldn't have counted 50 policemen at the stadium, the rest were from Angola, who were not familiar with the terrain, so they didn't know how to handle the situation.
"The Ghanaian fans were left at the mercy of these violent fans."
The Confederation of African Football has yet to make an official comment on the issue.
Ghana will face Ivory coast in the final on Sunday.
Watch every match of the Africa Cup of Nations LIVE on British Eurosport HD or sign up to Eurosport Player and follow the action on mobile, tablet and other devices: www.eurosportplayer.com
