Ban told a press conference that he has spoken with Yingluck and opposition Democrat Party leader Abhisit Vejjajiv in the past three days "in an effort to help them bridge their differences."
"I am very concerned that the situation could escalate in the days ahead, particularly next Monday, January 13, when protestors said they will shut down Bangkok," Ban added.
"I urge all involved to show restraint, avoid provocative acts and settle their differences peacefully, through dialogue," he said.
Thai authorities say they will have nearly 15,000 police and soldiers deployed in the capital for the planned "shutdown."
Yingluck has called a February election following weeks of opposition protests. But the demonstrators have vowed to block the vote, which they say will only prolong the political dominance of her wealthy family.