"Grievances must be resolved through appropriate legal mechanisms".
On Wednesday, the Kenyan government had said the TV stations would stay off air indefinitely.
Heather Nauert, the spokesperson for the State Department, said the US was "deeply concerned by the government's action to shut down, intimidate, and restrict the media".
Friday's arrest is the latest twist in the long saga of Kenya's disputed elections which saw the Supreme Court annul the result of the initial August poll and Odinga boycott the October rerun.
He also said the blackout had meant "significant financial losses" for the station, though he was unsure exactly how much money had been lost.
Two opposition politicians were arrested this week, and three journalists applied for "anticipatory bail" when they were tipped off that police had surrounded their offices to arrest them.
Kenya's Standard newspaper reported that "the young boy was shot after police officers engaged National Super Alliance (NASA) supporters protesting the apprehension of lawyer Miguna Miguna".
Hours after the leader in the opposition was taken to an unknown location for interrogation, youths allied to the opposition in Kenya went to the streets of Nairobi to demand his release, blocking roads with burning tires and boulders.
Worldwide calls for dialogue between the two sides have for months been ignored by both the government and opposition. In a statement released Wednesday, the day before the high court's ruling, Interior Minister Fred Matiang'i said the stations will remain shut throughout ongoing investigations into alleged complicity in what he called an effort to subvert the government and spark violence. "We've seen media houses being denied advertising, which is a crucial source of revenue".
KTN News, NTV and Citizen Television stations were shut down by the Communication Authority of Kenya early Tuesday minutes after they had started airing the event.
The government cut the live transmission of the country's top three TV channels Tuesday as a huge crowd of tens of thousands gathered in a Nairobi park for the mock inauguration.
ADDIS ABABA Ethiopia (Xinhua) - The Chairperson of the African Union Commission (AUC), Moussa Faki Mahamat, expressed concern regarding Kenya's current political condition.
On Tuesday, KTN News, NTV, and Citizen TV were blocked from broadcasting the "swearing-in" of opposition leader, Raila Odinga, in a mock presidential inauguration.
'Freedom of expression, including for members of the media, is essential to democracy and is enshrined in Kenya's Constitution.
"The Chairperson urges all concerned to desist from any such actions, which also put the political stability of Kenya at risk", the statement said.