US President Donald Trump attacked the California Governor on Monday, saying he was incompetent.

"The governor of California is incompetent and those who caused the violence should be imprisoned," Trump said in a speech.

"We made the right decision to deploy the National Guard to deal with the violent and inciting riots in California," he added, stressing,"We will do what is necessary to keep our citizens safe so we can make America great again."

The California governor said he would sue President Donald Trump over his decision to send the National Guard to Los Angeles amid protests against immigration policy.

Governor Gavin Newsom wrote on his social media page:"This is exactly what Donald Trump wanted. He started a crisis, then illegally tried to federalize the National Guard. The order he signed isn't just for California; it gives him the power to go into any state and do the same thing. We're going to sue."

A U.S. Immigration and Customs Enforcement (ICE) operation to round up undocumented immigrants in downtown Los Angeles on June 7 turned into clashes with protesters.