How did boris yeltsin respond to the communist coup attempt apex?

He told the Russian people that the coup was bad, advised all the people of Moscow against the coup, and openly supported Gorbachev.

Boris Yeltzin is a Russian President that the United States assisted to gain power in order to eliminate the residual of Soviet Union's influence in Russia.
Boris Yeltzin tends to favor policies that lean to Democratic principles, which is why he responded in such a way to the Coup.