Prime Minister Prayut Chan-o-cha on Thursday warned that the anti-government rally planned for Saturday poses a risk of a new surge in Covid-19 transmission.
More Covid cases would lead to business lockdowns and a further delay in the country's economic recovery, the PM said.
Speaking on TV Pool, the PM raised his fears about a second wave of the pandemic.
"When you gather in mobs, you are creating an enormous risk of new infections," he said.
"With that, you also create a great risk to the livelihoods of tens of millions of Thais."
He was speaking ahead of tomorrow's planned anti-government rally at Thammasat University's Tha Prachan campus in Bangkok. It is being led by the United Front of Thammasat and Demonstration (UFTD).
He said that he was aware that the protesters had political grievances and issues with the constitution. "I respect your opinions but right now, our country has very much more urgent and painful issues that need to be addressed," he went on.
"Let's try and get through this global crisis and defeat Covid together first. Then we can come back to politics."
Speaking at Government House earlier on Thursday, Prayut also warned the protesters not to intrude on government office buildings, which were protected by law.
Nonetheless, the PM promised that protesters would be treated "gently" during this weekend's rally, in order to avoid violence.
He claimed some people and groups were trying to instigate violence but the government was trying to avoid that.
Opposition parties showed support for the anti-government protest. The Pheu Thai Party said the demonstrators had the right to express their views, so the government should protect that right and allow them to use a public area for their rally.
The demonstrators are calling for the prime minister's resignation, the dissolution of parliament, a new constitution, an end to harassment of government critics and for the monarchy to be reformed.
