Blinken also confirmed a US diplomatic convoy had been fired upon on Monday, though those inside were unharmed, in what he called a “reckless” act.
Read more: US Congressman raises voice for Pakistan in letter to Antony Blinken
Blinken, in Japan for a meeting of G7 foreign ministers, held separate calls with the commanders of the Sudanese Armed Forces and the Rapid Support Forces paramilitary, spokesman Vedant Patel said.
“The Secretary expressed his grave concern about the death and injury of so many Sudanese civilians due to the sustained, indiscriminate fighting,” Patel said in a statement.
Conflict between the army and paramilitaries in Sudan has killed about 200 people and wounded 1,800 since a weeks-long power struggle erupted into deadly violence on Saturday.
Read more: US working to get dozens of Americans from Afghanistan: Blinken
The fighting is between the forces of two generals who seized power in a 2021 coup — army chief Abdel Fattah al-Burhan and his deputy, Mohamed Hamdan Daglo, who commands the powerful Rapid Support Forces.
When he spoke to the two men, Blinken “stressed the responsibility of the two generals to ensure the safety and wellbeing of civilians, diplomatic personnel, and humanitarian workers”, Patel said.
A ceasefire would “permit the delivery of humanitarian assistance to those affected by the fighting, the reunification of Sudanese families, and allow the international community in Khartoum to make sure its presence is secure”, he added.
Blinken suggested that even a 24-hour ceasefire could serve as a good starting point for lowering tensions, and warned that the fighting was “recklessly endangering” civilians and officials.
“I can confirm that yesterday we had an American diplomatic convoy that was fired on. All of our people are safe and unharmed,” Blinken told reporters.
“But this action was reckless, it was irresponsible and of course unsafe.”
On Monday, UN Secretary-General Antonio Guterres again called on Sudan’s warring parties to “immediately cease hostilities”.
Analysts say the fighting in the capital of the chronically unstable country is unprecedented and could be prolonged, despite regional and global calls for a ceasefire.
Battles have taken place throughout the vast country and there are fears of regional spillover. The conflict has seen air strikes, artillery and heavy gunfire.
The European Union’s ambassador to Sudan was attacked in his home in the city on Monday, the bloc’s top diplomat Josep Borrell said. A spokesperson told AFP the veteran diplomat was “OK” following the assault.