Thaksin Shinawatra has asked Thais to forgive and forget starting from Songkran Day.
The fugitive former prime minister, who is spending the holiday in Hong Kong, made the plea in a speech that was broadcast on the satellite station Channel 4 for the People.
"What grieves me is the loss of our good old culture. Thais used to be generous and caring. What happened has destroyed that spirit," Thaksin said.
"In the past, we helped one another but today we bare our teeth. We fight, shoot, stab, rob and threaten one another. I can't believe this is happening in Thailand after we have developed ourselves to a level close to becoming a developed country."
The political divide is worsening, he said, "because Thais do not forgive".
"We hold grudges. We slander one another and live with lies. Those who do not know the truth are misled.
"In every country plagued by conflicts, people try to avoid inciting hatred using false information. They don't want the repeat of what happened in Rwanda, when two radio DJs whipped up malice between two tribes. Eventually, genocide led to 800,000 deaths. The DJs were sentenced to life in prison. What they did achieved nothing except mountains of bodies.
"As tomorrow is Songkran Day, I would like to apply the concept of our good old traditions to all Thais," Thaksin said.
"Let's make April 13 the day we put everything behind us and be generous to one another like when disasters struck, whether it was the tsunami or the great floods, during which Thais lent a hand to one another.
"I love, respect and care for all Thais but you don't have to worry about me. I'm in good health. My only concern is for Thailand to be peaceful and Thais to love another once again."
While in Hong Kong, Thaksin is expected to meet with several former Pheu Thai Party MPs and other supporters.
He has already met with Metropolitan Police Bureau chief Khamronwit Thoopkrachang, who has drawn criticism for his oputspoken admiration of Thaksin.