Agence France-Presse reported that at least two men were injured after being sprayed with toxic water.
Earlier in the morning, car and motorcycle horns rang out in the capital – a way for hundreds of protesters to show their dissatisfaction.
People in Myanmar continue to protest, while workers begin a nationwide strike in support of ousted leader Aung San Suu Kyi.
Although it is a working day today, we will not go to work, even if we get a salary deduction, Hanin Thazin, 28, who works in a clothing factory, told AFP.
She was one of more than a thousand people who gathered in a park in Yangon Monday morning – the day after the coup, when the military arrested and placed several democratically elected leaders under house arrest, including Aung San Suu Kyi and President Wen. Maine.
Even in Mandalay, the second largest city in Myanmar, he trained more than a thousand protesters on Monday.
This weekend, tens of thousands demonstrated in the streets around Myanmar in the largest protests so far since the military coup.
The military council declared a state of emergency for one year and promised to hold new democratic elections. The coup was met with widespread condemnation from the outside world.