The call for Addis Ababa to take action came as new US envoy Mike Hammer and EU envoy Annette Weber visited Ethiopia to hold talks, including with TPLF leader Debretsion Gebremichael in Tigray.
"A swift restoration of electricity, telecom, banking, and other basic services in Tigray is essential for the people of Tigray," the two envoys said in a joint statement.
The diplomats also called for unfettered aid deliveries to Tigray and the neighboring conflict-hit regions of Afar and Amhara, and urged the government to lift restrictions on cash and fuel to Tigray.
Debretsion, who last week warned that key services would have to be reinstated in Tigray before negotiations could begin, offered "security guarantees for those who need to work to restore services", the envoys said.
"With this security assurance, there should be no obstacle for the restoration of services to begin," they added.
The envoys' visit partially coincided with a trip by UN rights experts to Ethiopia last week as the three-member team attempts to investigate abuses committed in Tigray during the war.
The UN Human Rights Council created the commission last December to probe alleged violations of international human rights, humanitarian and refugee law.
Ethiopia originally rejected the decision to create a commission, calling it "counter-productive", before eventually approving its arrival in the country.
"The Commission hopes that the government will provide it with unhindered access without delay, so that it may visit sites and speak freely and privately with survivors, witnesses, and other persons of interest," it said.
In recent weeks, Prime Minister Abiy Ahmed's government and the Tigray People's Liberation Front (TPLF) have both raised the prospect of negotiations to end the brutal conflict.
More than 13 million people need food assistance across northern Ethiopia, according to the UN.