
Surapong urged Thai diplomats to explain the political situation to foreign investors in their posted countries to restore confidence in the Thai political system and economy.
The PAD called a street protest on Sunday demanding the government halt its plan to rewrite the Constitution. A clash with anti-PAD groups on Sunday night caused injuries to nearly 20 people on both sides.
The PAD leaders vowed to stay on although the government took a step backward by calling for a referendum before a decision on amending the charter.
"Investors are worried about the situation and whether the protests might lead to an undesirable political incident as happened previously, but I'm optimistic that all parties should have learnt lessons and should know the limits," Surapong told reporters after meeting with 92 Thai ambassadors and consulates-general at the Foreign Ministry.
The sooner the street protests ended, the quicker investor confidence could be restored, he said.
"I ask our ambassadors and consulates-general to explain to foreigners that everything will go along with the democratic process," he said.
"There will be no more coups in Thailand since the one in September 2006 caused too much damage to the country," he said.
The roller-coaster stock exchange over the past few days after the protests would calm down as soon as the situation was under control, he said.
Foreign Minister Noppa-don Pattama told the US business community in Thailand during a luncheon speech that the demonstrations would not seriously rock the government's stability.
It could harm investor confidence in the long run if they escalated, he said.