The policy of separating children from their families has been in place and utilized by the previous Obama administration, but it is gaining criticism due to the large numbers of migrants seeking asylum.
Fonda - who's calling for 90 million Americans to protest in the streets this weekend - is no longer the "Easy Rider".
During the multiple-tweet rant, Fonda suggested that Trump's 12-year-old son Barron should be ripped away from his mother Melania and put "in a cage with pedophiles" to see if she will "stand up against" her husband then.
"I tweeted something highly inappropriate and vulgar about the president and his family in response to the devastating images I was seeing on television", Fonda explained in a statement to The Hollywood Reporter.
Israeli Drone Fires A Missile At A auto In Gaza
Israeli troops have killed more than 120 Palestinians and wounded over 3,800 since the weekly demonstrations began on March 30. Palestinian security sources said a drone had fired on people east of the al-Bureij refugee camp in the central Gaza Strip.
Actor Peter Fonda on Wednesday called on his Twitter followers to target Immigration and Customs Enforcement agents in large-scale protests by surrounding their homes and children's schools. "WE SHOULD FIND OUT WHAT SCHOOLS THEIR CHILDREN GO TO AND SURROUND THE SCHOOLS IN PROTEST", Fonda wrote in all caps. Fonda may be referring to the detention centers, but proponents of the child separation policy point out that it may not be safe for children to be mixed in with adults in a detention center setting, due to potential problems like pedophilia, according to the Daily Caller.
Fox News reported that Frank Sinatra's daughter, Nancy, tweeted support for Fonda, telling him to "say how you really feel, blues baby".
In separate tweets, Fonda also targeted Homeland Security Secretary Kirstjen Nielsen, White House press secretary Sarah Huckabee Sanders, and White House policy adviser Stephen Miller.
Trump's office did not explain why the Secret Service was notified about the offensive tweets, as they do not appear to represent credible threats and should be covered under the First Amendment.