Azerbaijan and Armenia agreed a ceasefire on Tuesday, after more than three days of deadly fighting in the mountainous region.
"Those who expect to preserve the status quo risk to see more outbreaks [of violence] that will be happening in regular intervals," Steinmeier said after a phone call with the Armenian president.
Steinmeier described the truce as "very fragile" and said actions had been taken to defuse the current tensions and resolve the crisis once and for all.
The conflict in Nagorno-Karabakh began in 1988, when the Armenian-dominated autonomous region sought to secede from the Azerbaijan Soviet Socialist Republic, before proclaiming independence after the collapse of the Soviet Union in 1991. The warring sides agreed to a cessation of hostilities in 1994.