The convoy will carry much needed supplies to Tyre and a nearby village despite Israeli warnings that any car south of the Litani river will be fired upon.
Huwaida Arraf, a former co-founder of the International Solidarity Movement (ISM), said: "We are trying to let the whole world know that there is no justification for Israel's aggression in Lebanon."
ISM is a group initially formed to direct non-violent resistance to the Israeli military in the Palestinian territories.
The convoy will include Lebanese, Syrian, Saudi, Tunisian, EU and US citizens.
"International civilians have come here in response to call by Lebanese civilians," said Arraf.
Danger and death
The activists will face a dangerous trip to the south. Earlier on Friday, a civilian car travelling next to a UN aid convoy north of Tyre was hit by an Israeli missile killing two people.
Arraf said she was aware of the risk, but said the activists felt that something must be done to protest against Israel's offensive in Lebanon that has killed more than 1,000 Lebanese.
"No one going is wanting to die, but we know that we must stand up to Israel," Arraf said.
"We have been doing as much as we can to make our intentions clear that this is a civilian convoy," she added.
The convoy also faces other logistical problems. Bridges on the road south have been destroyed making it impassable in places and getting petrol for the cars has been a problem due to a fuel shortage in Lebanon.
Another activist who helped organise the convoy said she hoped to show the world a different side of the conflict.
Kirsten Idriss, a publisher, said: "Its a rejection of the idea that is being used to sell this war that Hezbollah is a cancer within Lebanon in the Lebanese body and only Hezbollah is being targeted. On the contrary all of Lebanon is being devastated.
"We need people in Beirut to create a sense of solidarity to show that we care about the people in the south," Idriss said.
Arraf says the activists are planning further actions.
"This is not the last effort. This is the initiation of a campaign," she said.