After new border battles occurred between the old adversaries, EU president Charles Michel urged Armenian and Azerbaijani authorities to call a "complete ceasefire," according to ALARABIYA.
Michel, the European Council's president, said he had spoken with Azerbaijan's President Ilham Aliyev and Armenia's Prime Minister Nikol Pashinyan.
Michel did not assign responsibility for the region's "difficult situation," but he did call for a "immediate de-escalation and full ceasefire."
He tweeted, "The EU is committed to working with partners to resolve tensions for a prosperous and stable South Caucasus."
Armenia has already reported the deaths of some of its personnel and the loss of control of two military sites near the Azerbaijan border.
Azerbaijan accused Armenia of starting the conflict and said that two of its soldiers were injured.
The fighting erupted a year after the neighbours waged a six-week conflict that resulted in the deaths of over 6,500 people and was terminated by a Russian-brokered truce.