President Reagan conceded last night that his Iranian policy had turned into an arms-for-hostages arrangement, and said, "I would not go down that same road again."

At his first news conference in four months, Reagan said again he was unaware until last November that profits from the arms sales had apparently been funneled to Contra rebels in Nicaragua, and said he still does not know what happened to the money.

At a question and answer session dominated by the Iran-Contra affair, Reagan also said he had never deliberately lied to the public, while admitting to a misstatement at his last news conference in November. "I'm not going to tell falsehoods to the American people. I'll leave that to others,'' he said after being questioned insistently on the subject.

He told one questioner that for some time, "all you knew was what I told you."

Asked whether disclosure of the affair had complicated efforts to free remaining hostages, the president turned the question around.

"The day that the information leaked it was my understanding that the other two were due to get out in the next few days," he said. "If it hadn't leaked I don't know...whether we would have gotten more out."

Reagan opened the 39th news conference of his presidency by uttering a "rock solid" pledge to veto any attempt in Congress to raise income tax rates. And he called on the House and Senate to adhere to the requirements in Gramm-Rudman legislation to make new spending cuts.

"It's time for Congress to cut the federal budget and leave the family budget alone," he said.

The news conference was the first since Nov. 19, a four-month period of political and personal trial for Reagan.

The Iran-Contra affair has mushroomed into a full-fledged scandal in the intervening months, with the president's popularity plummeting in the polls to the lowest level of his presidency. On the personal side, Reagan underwent prostate surgery on Jan. 5, and spent several weeks working on a reduced schedule.

Thus, many Republicans in Congress and some administration officials said in advance that Reagan needed a skillful, polished performance at the news conference to still any doubts about his ability to lead the nation for the next two years.