Ali Anouzla, director of the Arabic version of independent news website Lakome, was arrested on September 17 after his website posted a link to the video attributed to Al-Qaeda in the Islamic Maghreb (AQIM), the extremist network's North African affiliate.
He was subsequently charged with defending and inciting terrorism, according to his lawyers.
"We are concerned with the government of Morocco's decision to charge Mr Anouzla," US State Department deputy spokeswoman Marie Harf said.
"We support freedom of expression and of the press, as we say all the time, universal rights that are an indispensable part of any society," she added.
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Harf confirmed Washington had been in direct contact with Moroccan officials over the case, which has triggered an outcry from from rights groups in and outside of Morocco including Amnesty International and Reporters Without Borders.
Police arrested Anouzla after a Lakome article carried a link to the website of Spanish newspaper El Pais, where the Al-Qaeda video had been posted.
The 41-minute video, entitled "Morocco: the kingdom of corruption and despotism," first appeared online on September 12. It calls for jihad in the North African country and lashes out at King Mohamed VI.