President Reagan, "ticked off" by media coverage of his decision to limit arms to Taiwan, last night called CBS anchor Dan Rather in the CBS newsroom between the first and second "feeds" of the "Evening News" to explain his decision.

Rather gave details of his conversation with the president on the air during the second feed of the newscast.

Rather said later that the president told him, "I just watched you, and I'm concerned and upset about the coverage of Taiwan." Rather said he asked Reagan if he was talking about CBS' reporting or interpretation. Reagan answered, "The coverage has not been right all day. Dan, I want you to understand there's been no retreat and no change in our policy. We'll continue to arm Taiwan." Rather described the president as "friendly but firm."

Rather said Reagan did not raise his voice and referred to nothing specific in the three reports CBS had broadcast about the Taiwan arms negotiations.

"He sounded concerned and maybe a little hurt. He could not have been nicer. I said to the president, 'I'd like to talk to you. Is this a personal call or could I broadcast the tone of your remarks?' The president said, 'You go ahead,' and I said, 'I'll do what I can.' "

The "CBS News' " first feed is at 6:30 and is updated at 7. It was seen on Channel 9 here. The president was watching the first feed from Channel 11 in Baltimore.

The call came just before the 7 o'clock broadcast. The three segments on Taiwan aired unchanged, but during the second broadcast Rather came on the air immediately after the Taiwan coverage and ad-libbed for about a minute and 15 seconds, relating the gist of the president's comments.

White House deputy press secretary Larry Speakes said, "We went away happy" after hearing Rather's revised broadcast. "He quoted the president fairly accurately."

He said the president had been watching the news with Chief of Staff James A. Baker III and Deputy Chief of Staff Michael K. Deaver up in the president's private quarters. "They were concerned about the CBS treatment of the Taiwan story," said Speakes.

After the Taiwan segments were broadcast, Speakes joined the two other presidential aides, who reported that the president was "ticked off." When one of them suggested that he was about to telephone the program to register a complaint, it was suggested, "Maybe the president might want to call himself," Speakes said. And after a brief discussion with the president, Reagan placed the call at 6:55.

Rather said when the phone call came through "it was the switchboard saying the White House was calling, and a young woman on the CBS staff, Terri Belli, took the call. But since we get a lot of freaky calls here at CBS News, she took a little time determining it was the White House calling."

Rather said he got on the phone after they verified it was the White House, was told to "hold on for the president," and was promptly disconnected. About a minute into the second feed the call from the president came through.

Speakes said it was the first time the president had called a network about its news coverage. He said Reagan had phoned columnist James J. Kilpatrick one Saturday evening recently after the columnist had defended the president during a broadcast of "Agronsky & Co."

After the president's call last night, both Rather and "ABC Nightline" anchor Ted Koppel contacted the White House to see if the president would agree to be interviewed tonight on their broadcasts. Speakes said he doubted that the president would.