President Reagan "has never felt better" and believes he would be "bored" if he does not run for reelection in 1984, he told the Los Angeles Times in an interview published today. But Reagan, 72, revealed that he is feeling some signs of his age.

The president's remarks on his age and health apparently were aimed at reassuring voters, potential opponents for the '84 presidential election, and a sometimes-combative Congress.

"No, that health could never be a factor" in deciding on a reelection bid, Reagan said in an interview aboard Air Force One on his way here for a holiday weekend at his ranch.

The interview was granted by the White House on condition that the questions be restricted to Reagan's health and age, and White House advisers said today they were trying to send a message.

"Everyone can see this is an undercurrent for 1984," a senior administration official said. "Too much interest is shown in Washington in his gray hair, his hearing, and we get phone calls whenever he forgets a question or has an interview where his thoughts are not coherent.

"With a young man it would be a bad day . . . ; with him it is the first sign of senility to the Democrats. We want to cut this off right now."

The interview quotes an unidentified Reagan intimate as saying: "Mr. President, the way you've got to look at this is that the odds are, if you run for reelection, you'll spend the rest of your life in the White House."

In the interview, the president said that a relatively rare hereditary illness called Dupetron's Contractions has caused a tendon in his hand to stiffen, involuntarily curling the fourth finger on his right hand. And Reagan said the hearing in his right ear "continues to deteriorate."

Although the president said he is eager to keep up what he is doing, he acknowledged that his memory occasionally has failed him for many years, dating back to his days as governor.

The president did not say whether he suffers any lingering distress since being wounded in an assassination attempt in March, 1981. Dr. Daniel Ruge, White House physician, said today that Reagan is in excellent health and will not need a physical examination this year.

The president, who is 6-foot-1 and weighs about 190 pounds, told the Times that he has added five pounds of muscle to his weight by working out daily with pulleys and weights. He said he watches his weight, but not so closely as to not "spring for" a platter of Mexican food occasionally.

"I figure I've got that coming," he said.

Reagan's health and age have become a large concern as he approaches the decision to be made later this year on seeking another term. White House advisers long have expressed anxiety about questions concerning the fact that Reagan would be 78 years old in the final year of his second term and the underlying negative image that might present to voters.

When asked what his life would be like if he chooses not to run again and retire to his ranch in Santa Barbara, which he has visted about once very two months during his presidency, he said: "I think I'd get bored," and then added suddenly, "I'm not saying I'm going to run ."

Reagan said he has been keeping a diary to help with his memory and has begun to compensate for his hearing by turning his head in the direction of persons speaking to him.

Reagan attributed his generally good health to riding horses four times a week "during that television span of my life," in the late 1950s.