His Majesty the King wrote messages of national unity and love on Tuesday during a visit to Udon Thani two days after protesters sent him a letter demanding royal reforms that would curb his powers.
The Royal Household Bureau has made no comment on months of protests so any communications from the king are watched carefully in the Southeast Asian country.
"We all love and care for each other. Take care of the country, help each other protect our country with goodness for prosperity and protect Thainess," the King wrote in a message to the Udon Thani governor.
On a picture of himself and the queen that was brought by one of the crowd of well-wishers, the King wrote: "Love the nation, love the people, cherish Thainess, real happiness."
Thousands of protesters marched to the Grand Palace on Sunday, getting within a few dozen metres of the walls despite a police blockade and a burst of water cannon, to send a message to the King.
Shattering a longstanding taboo on criticising the monarchy, they have demanded the departure of Gen Prayut Chan-o-cha as prime minister, a new constitution and reforms that would reduce his powers.
"When the King truly cherishes democracy, all people will find happiness," the protesters said.
On Nov 1, His Majesty made his first comments on the protesters. In brief remarks, he said "we love them all the same" and describing Thailand as a land of compromise.
Gen Prayut has said he will not resign, rejecting protesters' accusations that he engineered last year's election to keep power that he seized in a 2014 coup.
Pictures from different royal events in Udon Thani showed thousands of people. Many wore yellow shirts - matching the king's colour - and carried matching official portraits of the royal couple.