The video featured in the media player above is the ABC7 Los Angeles 24/7 streaming channel
In the video captioned "Saving LA-Phase III" posted on his social media, Pratt said he is not leaving town.
"You thought you could get rid of me that easily?" Pratt said. "I didn't get in this for political power, I got in this to expose this corrupt machine and nothing's changed."
"And now I don't have to worry about offending CNN viewers. I don't have a campaign to hamstring me now. It's war,' he added.
The three-minute video featured clips from movies, news broadcasts and even a UFC fight.
Pratt went on to criticize the remaining candidates, City Councilwoman Nithya Raman and Mayor Karen Bass.
"Angelenos are now stuck with two morons responsible for all their problems and now have to choose between dumb and dumber," Pratt said, as images of Raman and Bass appeared.
He also said that "every problem that plagues Los Angeles because of these two corrupt communists is going to accelerate" under their leadership.
Pratt said they have a recording of one of the candidates "doing or saying something that would make her resign in shame," but did not directly say whether it was of Bass or Raman.
He claimed major developers, hoteliers, business owners and entrepreneurs have told him they are leaving the city, which he argued would lead to more restaurant closures and less tax revenue.
"That means the city has to cut services. More potholes, less firefighters, less police patrols, more criminals, more drug addicts terrorizing your communities," Pratt said.
"You have no idea how bad things are about to get for the city, look at this place already," he added. "The city is a mess and you're about to reward the arsonist who torched the place with four more years of destruction."
Pratt competed against Bass and Raman in the primary election for a spot in the November runoff. He was eliminated after failing to secure enough votes to advance.
His video message comes just one day after Raman made a pledge to his supporters to deliver on the change they want in an effort to be their candidate come November.
The election was not a vote of confidence in Bass, who, according to incomplete returns, received under 35% of the vote, a vulnerable position for an incumbent.
Raman holds a lead of more than 29,000 votes over Pratt in the latest election results, with 246,333 votes to Pratt's 216,783.
Raman, who previously endorsed Bass for reelection, had been running in third until Sunday, but she gained more votes with every update provided by election officials in Los Angeles since June 2, primary day.
ABC7 reached out to Raman's campaign, who had no comment about Pratt's video.
Pratt's candidacy drew national attention due to his celebrity status and outspoken criticism of liberal leadership in a heavily Democratic city, but that attention did not translate into sufficient support at the polls.
Angelenos will decide in November whether Bass keeps her position as mayor or if voters turn the page and elect Raman as the new leader for the city.