Condoleezza Rice -- Gabby Douglas is an African-American Hero

Condoleezza Rice is a big fan of U.S.gymnastics superstar Gabby Douglas ... telling TMZ she's "thrilled" for the 16-year-old's "momentous accomplishment as the first African-American" to win a gold medal at the Olympics in the all-around competition.

Rice says she's been following the ENTIRE U.S. Women's Gymnastics team at the 2012 Games ... telling us the girls have been "incredible" to watch.

"Proud of their team gold and thrilled for Gabby Douglas and her momentous accomplishment as the first African-American to win the individual all-around gymnastics title, " Rice says.

She adds, "These young women are full of grace and poise."