Bekele and Demissie are the last defendants of 131 people originally charged following street protests that started after an election was disputed in 2005. More than 193 people died in the ensuing conflict with the authorities.
Bekele, who worked for ActionAid, and Netsanet, who worked for an aid group supported by ActionAid, were involved in deploying observers at polling stations in and around the capital, Addis Ababa.
Julian Filochowski, an official with ActionAid International, said: "We are shocked and dismayed by the verdict as they were acquitted from the major charges and found guilty on lesser ones.
"They belong to civil societies and are just trying to defend their activities," he said.
Prosecutors in the trial called for a revocation of the defendants' civil liberties, citing civilian casualties and property damage which resulted from the chaos that followed the polls.
At least 193 civilians and six police officers died in Addis Ababa during post-election violence in June and November 2005.
In August, the court freed 31 members of the opposition Coalition for Unity and Democracy (CUD), also held since the polls.
Another 38 opposition members, including Hailu Shawel, the CUD chairman, were pardoned and released in July after the government said they signed a letter admitting their guilt and pledging to respect the law.
But the two activists had refused to sign a formal apology, preferring to fight their case in court.
|More than 130 people, including opposition |
figures and activists, were charged [EPA]
Kumi Naidoo, secretary-general of Civicus, a network of civic rights campaigners, told Al Jazeera that Bekele and Demissie took a principled decision not to sign the admission.
"They thought that doing this would criminalise the work of civil society in Ethiopia," he said.
"In April, when the prosecution presented evidence in April against them, the presiding judge at that time said they didn't have a case to answer.
"Unfortunately, the associate judges took a different view. As was the case today.
"The presiding judge again took the view that they were not guilty of the lesser charges."
The case was strongly criticised by rights groups and donors who saw it as an attempt to dismantle the opposition after it made strong gains in the election.
Naidoo said: "Given that Daniel and Netsanet had appealed at least seven times for bail in the last two years and three months, it would be fair to assume that they would exhaust all legal options available to them.
"To them, it's not simply about walking out of prison, as they could have done six months ago. They want to ensure that they do not undermine the work of human rights campaigners, anti-poverty campaigners and other civil society groups."
Following the court's verdict on Monday, Demissie said: "Whatever we did during the election, we did with the good and honest intention of respecting the constitution of our country."