* Scores march peacefully, main protests may be in afternoon
* Bahrain has banned protests in Manama, toughened laws
* "Tamarrod" says it wants free and democratic Bahrain (Adds peaceful protests, Bahrain mainly quiet at mid-day)
MANAMA, Aug 14 (Reuters) - Bahrain tightened security around some restive Shi'ite Muslim villages to try to prevent anti-government protests planned for Wednesday that have prompted the United States to close its embassy temporarily.
Up to 100 people marched peacefully in the village of Saar west of the capital Manama in the morning, waving Bahraini flags and chanting anti-government slogans, Reuters witnesses said.
The protest dispersed peacefully before security forces arrived at the scene, and residents said any larger protests were not expected until late afternoon.
Activists have called on social media for people to meet near the U.S. embassy, saying they would try to force the Sunni Muslim ruling family to allow more democracy in the country of 1.25 million.
Their loose association of groups has drawn inspiration from an Egyptian movement that staged protests leading to the overthrow of President Mohamed Mursi last month.
However, while the Egyptian protesters were backed by the military, Bahrain's security forces remain loyal to a government that vowed on Monday to "forcefully confront" demonstrators and prosecute those responsible for "incitement".
The Interior Ministry reported that an Asian worker was injured by a firebomb as he tried to open a road blocked by protesters in a village south of Manama, and said burning tyres had been used to block a main road in Muharraq, northeast of the capital.
It described the acts as "terrorism", for which new laws passed this month allow tougher penalties including longer prison terms and the stripping of Bahraini nationality.
The small Gulf Arab state and Western ally that hosts the U.S. Fifth Fleet has had bouts of unrest since February 2011 when an uprising led by members of the Shi'ite majority demanded the al-Khalifa dynasty give up power.
The authorities crushed the revolt but protests and clashes have persisted despite talks between government and opposition, leaving Bahrain on the front line of a tussle for regional influence between Shi'ite Iran and Sunni Saudi Arabia.
Bahrain's largest opposition group, the Islamist al Wefaq Society, said it was not planning to join the protests officially but supported the right to peaceful demonstrations.
"I know that it is going to be a peaceful movement but, having said that, I also expect clashes between the government forces and the protesters, because they are against all protests and demonstrations," Wefaq leader Sheikh Ali Salman told Reuters.
Wefaq said in a report on its website late on Tuesday that security forces had ringed some areas with barbed wire and blocked some streets with concrete barriers. But by midday on Wednesday, only minor incidents were reported.
On Tuesday night, Bahrain deployed extra forces in areas where there has been regular unrest over the past two years. In some villages, all shops were closed. In Manama, where the government has banned protests, businesses were open but there was a bigger police presence than usual. In the Bab al-Bahrain commercial district police in riot gear sat in a parked bus.
Security forces were also monitoring traffic on roads leading into the capital, occasionally stopping vehicles to check identity papers.
The new push for a "free and democratic Bahrain" is being driven by "Tamarrod" (Rebellion), a loose association of opposition activists who came together in early July, according to social media quoting the group.
This is named after the Egyptian movement that staged protests against Mursi and his Muslim Brotherhood before the military removed the country's first freely-elected president.
In Cairo, Egyptian security forces killed at least 30 people on Wednesday when they moved in to clear a camp of protesters demanding Mursi's reinstatement, the Brotherhood said.
Complaining of discrimination against majority Shi'ites in areas such as employment and public services, the Bahrain opposition is demanding a constitutional monarchy with a government chosen from within a democratically-elected parliament. The government denies any discrimination.
The U.S. embassy advised Americans to avoid non-essential travel inside the country and said it would close on Wednesday.
"I don't see where the problem is, why we are not allowed to ask for our demands and needs in peaceful demonstrations," a 24-year-old secretary, who asked not to be named, said.
But a 34-year-old banker, who also asked for anonymity, said such protests were intimidating.
"The anti-government societies tried to scare us on February 14 of this year ... but thanks to the forces they were not able to do anything," he said, referring to an earlier call for protests to mark the second anniversary of the 2011 uprising. (Writing by Sami Aboudi; Editing by Elizabeth Piper and David Stamp)