It was not immediately clear who was behind the messages, which appeared on several different channels available through a local cable broadcaster.
A Wenzhou resident surnamed Gu told AFP that he had turned on his television on Friday evening to be greeted with a photo of a tank on Tiananmen square.
“I found it irritating. ... It doesn’t feel right to vent your opinions by sacrificing others' interests," he said, adding that similar images and anti-Communist slogans were broadcast for about four hours.
Another local resident who declined to be named said that his TV had shown a slogan saying: "Bandit Communists you’ve done too many evil deeds and now you’re feeling guilty."
"At the moment some areas of Wenzhou city are receiving unusual broadcasts, technical staff are currently trying to solve this issue, we hope viewers will understand,"the Wenzhou branch of China Cable, said on Sina Weibo, the Chinese equivalent of Twitter.
Several photos posted on Sina Weibo — which were later deleted — showed a TV screen displaying a banner which read "Free Wang Bingzhang", referring to a Chinese pro-democracy activist jailed for life in 2003.
"Damn the Chinese Communist Party's mouthpieces: China Central Television, Peoples' Daily," read another message.
"Communist bandits are the real criminals," a message shown in the corner of one viewer's screen added.
Another photograph showed the channel displaying the iconic "Tank Man" photo from the 1989 crackdown, showing a lone man standing in front of a column of tanks.
Cable viewers also saw a message reading "Friends, don't co-operate with Communist devils," superimposed on a broadcast of a basketball game.
Subscribers were also shown graphic images showing apparent human rights abuses in the country, such as a protester being squashed under a truck.
China's Communist party does not tolerate organised dissent, and has regularly jailed members of any group which challenges its right to rule the country.
Internet users expressed surprise at the broadcasts, which were said to have ended late Friday, with some speculating that hackers were behind the attack.
"This is a significant event for the television industry," one Sina Weibo user wrote, while another said: "It seems that Wenzhou has been hacked, haha haha."