"The troops opened fire to frighten residents after reaching the governor's office," he said, quoting witnesses in the eastern city.
There were mounting fears the army was preparing to crack down on Deir Ezzor, increasingly at the forefront of more than four months of protests against the autocratic regime of President Bashar al-Assad.
"People chanted 'Allahu akbar' (God is greater) in the city as a warning against a huge military operation and residents began setting up sand barricades to prevent the army from spreading into the city," Abdel Rahman said.
As the tanks and military vehicles rumbled towards Deir Ezzor they were confronted by an angry mob from the nearby village of Tibneh who hurled stones at the troops to stop their advance.
"The soldiers opened fire on them to disperse them, killing three people," the activist said by phone from Britain.
Tibneh is about 40 kilometres (32 miles) west of Deir Ezzor, where hundreds of thousands gathered Friday for the funeral of three people killed by security forces the previous day, according to activists.
Deir Ezzor, the main oil- and gas-producing region in Syria, which produces 380,000 barrels of oil per day, has seen almost daily demonstrations against the regime.
Protests have swelled on Fridays -- the day of rest when devout Muslims gather in mosques for key noon prayers -- across the city and the province also called Deir Ezzor.
On July 13 a rare explosion hit a gas pipeline near the provincial town of Mayadin -- in the first such act of defiance against the regime since pro-democracy protests broke out in mid-March.
Another blast on Friday rocked an area near Homs, a flashpoint protest city in central Syria, only hours before nationwide anti-regime protests, with officials blaming the attack on "a subversive group.".
Riad al-Asaad, who identified himself as a colonel who defected from the Syrian army, warned authorities against carrying out any operation in Deir Ezzor.
"I warn the Syrian authorities that I will send my troops to fight with the (regular) army if they do not stop the operations in Deir Ezzor," Al-Asaad said.
"I am the commander of the Syrian Free Army," he said, adding that he commanded "hundreds" of troops and was calling from inside Syria "near the Turkish border." The claim could not be independently verified.
Meanwhile an opposition figure who declined to be named told AFP that 15 conscripts broke ranks from the troops who entered the city on Saturday and fled. "They have sought protection with residents," the source said.
On Friday at least three people were killed in Deir Ezzor when security forces opened fire on 300,000 mourners who attended the funerals of three people killed there the previous day, activists have said.
A total of 20 people were killed and 35 wounded on Friday across Syria as hundreds of thousands of demonstrators held anti-regime protests, according to the National Organisation for Human Rights and the Syrian Observatory.
The victims included a young man shot dead when Syrian forces raided at dawn the Qadam neighbourhood in Damascus, the Observatory's Abdel Rahman said.
"Soldiers and a large number of security agents entered Qadam at 3:00 am on Friday (0000 GMT) and cordoned off the area," he said.
"More than 500 people were arrested during the operation, and one young man was killed at a security roadblock," he said, adding that the victim was quickly buried as authorities banned public funerals in the area.
Friday's protests, called for by Facebook group The Syrian Revolution 2011, were aimed at putting pressure on the rest of the world to act in the face of the deadly crackdown.
"Where are you, defenders of freedom?" and "Enough of your silence..." the group said on its website.
Meanwhile 50 Syrian opposition figures meeting in Algiers on Saturday spoke out against foreign intervention in their country, and against carrying arms.
"We refuse all foreign intervention, we refuse to carry weapons," said Adnane el-Bouch. "Our weapons are cameras and mobile phones."
Delegates also observed a minute of silence for children killed in the crackdown, and published a list of 85 names of victims aged three to 17.
More than 1,500 civilians have been killed in the government's crackdown of protests since mid-March while 12,000 people have been arrested, rights groups say.