The United States urged the Nicaraguan government to "cease using excessive force on peaceful protesters and journalists exercising their right to a free press."
"Democratic voices will never be silenced by crude brute tactics," Assistant Secretary of State Kimberly Breier said on Twitter. "The world is watching you, too."
The US Embassy urged its citizens not to take part in demonstrations and to avoid areas where protesters gather.
Read more: Nicaragua orders UN human rights delegation to leave
Vatican's intervenes on behalf of prisonersProtests against Ortega first started in April 2018, with opposition umbrella group Civil Alliance accusing the left-leading 73-year-old leader of corruption, brutality and incompetence. The government responded with a brutal clampdown. Observers estimate that over 500 people have been killed and hundreds more arrested. Nicaraguan authorities have also banned anti-government protests.
The government pledged on Friday that it would move 50 opposition prisoners to house arrest. The Saturday event was set to call for more political prisoners to be released.
Hours after 107 protesters were arrested in Managua, the national police announced all of them would be released following an intervention from the Vatican's ambassador in Nicaraguan capital.
Ortega has ruled the Latin American country since 2007. The former guerilla commander also served as leader between 1979 and 1990.
dj/sms (dpa, AFP, Reuters, AP)