"We want any kind of action. The world has stood silently and it's been too long. Something needs to be done," said Tamer Barazi, a 23-year-old civil engineer who carried a Syrian flag and a sign stating "Syrian Americans for peace, democracy and freedom in Syria."
Standing across the street in Houston's sweltering heat were those opposing U.S. intervention, outnumbering the supporters of an intervention. Some carried signs stating "We Don't Want Obama's War" and "Hands Off Syria."
"How would you like another country to decide who is going to be the president of the United States?" asked 53-year-old Hisam Saker, a Syrian-American property manager who has lived in Houston for 33 years.
In Washington, as Obama addressed the nation from the Rose Garden, crowds of anti-war demonstrators gathered outside the White House. "Obama, hands off Syria" shouted the anti-war demonstrators, who carried yellow signs reading "No War On Syria."
Across the street, Syrians and Syrian Americans who support U.S. action waved flags from their country and shouted for Assad's ouster.
"The conflict's been going on for, what, almost 2 years now. Estimates are 100,000 Syrian civilians have been killed and all of a sudden the U.S. government has manufactured the excuse of the use of chemical weapons in Syria to use that excuse to intervene in Syria," said Tristan Brosnan, 25, of Washington.
In London, more than 1,000 protesters carrying Syrian flags and placards marched to Downing Street and rallied in Trafalgar Square.
And about 700 people turned out for an anti-war demonstration in Frankfurt, Germany, police said. Organizers said only a "sovereign, independent Syria free of foreign interference" would make it possible for the Syrian people to shape the country's future.
At a protest organized by left-wing opposition parties in Amman, Jordan, Kawthar Arrar described any military intervention as "an aggression on the whole Arab world." The protesters gathered outside the U.S. embassy, chanting slogans and setting fire to American and Israeli flags.
U.N. inspectors left Syria on Saturday after a four-day, on-site investigation in the area where the chemical attack is suspected.
The protesters in London hailed Thursday's U.K. parliament vote against British participation as a victory.
"Chemical weapons are terrible weapons, but when you think of all the thousands of people that have been killed by British and American troops in Afghanistan and Iraq you realize that it isn't true that another war would solve the problem," former Labour Party lawmaker Tony Benn told the protesters.
Watch The Associated Press video at: http://www.youtube.com/watch?v=WELrVc43hk&feature=share&list=UU52X5wxOLs5yw0dQk7NtgA
Associated Press writers Steve LeBlanc and Rodrique Ngowi in Boston, Geir Moulson in Frankfurt, Sylvia Hui in London and Eric Tucker in Washington contributed to this report.