US President Barack Obama on Friday praised the courage of dissidents fighting for democracy in Muslim countries, in a message marking the start of the Muslim holy month of Ramadan.

"On behalf of the American people, Michelle and I extend our warmest wishes to Muslim Americans and Muslims around the world at the start of Ramadan," Obama said in a statement.

Although he did not mention by name the "Arab Spring" uprisings against authoritarian Arab rulers, Obama said "this year, Ramadan holds special meaning for those citizens in the Middle East and North Africa who are courageously achieving democracy and self-determination and for those who are still struggling to achieve their universal rights."

The president vowed that "the United States continues to stand with those who seek the chance to decide their own destiny, to live free from fear and violence and to practice their faith freely," likely referring in part to the escalating violence in Syria.