The lawmakers had planned to tour a nearby sugar factory before driving north to Kunduz province.
As in the nineties, the militias around Kunduz have begun fighting each other for territory.
The airstrike occurred Thursday after fuel trucks were hijacked by militants in the Kunduz province.
The Germans will take a few hundred men north to the stable backwater of Kunduz.
The attack took place at around 1720 local time (1250 GMT), a Kunduz police spokesman said.
The battle of Kunduz is important because this is the land route the food will pass through.
Since the Germans took over in Kunduz on January 1st, there have been no further deployments outside Kabul.
Speaking to troops at the Kunduz base, Mrs Merkel praised their bravery and said their mission was vital.
BBC: Germany's Merkel makes unannounced visit to Afghanistan
The American diplomats responsible for Kunduz are stationed seventy-five miles away, in a heavily fortified base in Mazar-e-Sharif.
Now the Kunduz airstrike has become the catalyst to help Germany redefine the Afghan operation in more warlike terms.
It wants to send 450 German peacekeepers to Kunduz, a region in the north, to help with reconstruction efforts.
The road from Kunduz city to Kabul is dangerous to travel, and the city's airport closed to commercial flights months ago.
BBC: Germany's Merkel makes unannounced visit to Afghanistan
Also last month, four Afghan policemen were jailed for 16 years for raping a young woman in northern Kunduz province this year.
Much of the violence and disorder in Kunduz, as elsewhere in Afghanistan, takes place beyond the vision of American soldiers and diplomats.
Saturday's confrontation in Kabul came as thousands of demonstrators unsuccessfully tried to storm the United Nations compound in the northeastern city of Kunduz.
The fuel trucks were hijacked late Thursday in Kunduz province and were spotted several hours later on the banks of the Kunduz River, ISAF said.
Mrs Merkel arrived early on Saturday in Kunduz, where Germany has a base, accompanied by Defence Minister Karl-Theodor zu Guttenberg and military Chief of Staff Volker Wieker.
BBC: Germany's Merkel makes unannounced visit to Afghanistan
The federal prosecutors seem to have endorsed this shift by deciding not to charge the German commander who had ordered in the Kunduz airstrike with war crimes.
In August 2010, the Afghan authorities released a video showing a couple being stoned to death in Northern Kunduz province after a Taliban court found them guilty of adultery.
The German Defense Ministry in Berlin confirmed a bomb attack near a base that houses a German provincial reconstruction team in the town of Kunduz, a ministry spokesman said.
There was tight security as Mrs Merkel visited the main German base at Camp Marmal, outside Mazar-e Sharif, but a trip to another base at Kunduz was cancelled because of bad weather.
BBC: Afghanistan: Germany's Merkel in troop deadline warning
应用推荐