Earlier, the militant group said it was behind the killing of a senior Supreme Court official in the capital, Kabul.
Meanwhile, Nato said two of its soldiers were killed in an insurgent attack close to the main international base to the north of Kabul.
The incidents come amid an upsurge of Taliban violence as the US and Nato mission in Afghanistan nears its end.
Taliban fighters attacked the landmine-clearing operation early on Saturday, shooting 12 workers dead and injuring another 12, police spokesman Farid Ahmad Obaid told reporters.
He said Afghan soldiers later took on the militants in a gun battle, killing four and capturing three.
Afghanistan is one of the most heavily mined countries in the world and clearing projects have been targeted by Taliban militants in the past. In April, Taliban gunmen killed 12 landmine clearers in Logar province.
Earlier on Saturday, police in Kabul said Atiqullah Rawoofi, the head of the Supreme Court's secretariat, was shot dead by two men on a motorbike as he walked from his home to his car.
Nato soldiers killed
Saturday's violence was just the latest in a series of militant attacks against Afghan and Nato targets.
Late on Friday two Nato soldiers died when a convoy was attacked by militants near the Bagram air base in Parwan province near Kabul. The nationality of the soldiers was not released.
They were the first foreign troops killed in December, and their deaths mean 65 international troops have now been killed in Afghanistan during 2014, 50 of them from the US.
On Thursday a teenage suicide bomber blew himself up in the auditorium of a French cultural centre in Kabul during a performance of a play condemning violence. One German national was killed and 16 people were injured.
Last month, Kabul's police chief resigned following several attacks on foreigners and locals in the city.
Most foreign forces will leave the country in under three weeks, although about 12,000 Nato soldiers will remain to train and advise Afghan security forces from 1 January.
The BBC's Mike Wooldridge in Kabul says the recent violence has provoked fresh debate about how the Taliban have been able to evade the apparently rigorous security in the capital.
President Ashraf Ghani, who took power in September, has vowed to bring peace after decades of conflict.
