President Reagan yesterday announced that he is imposing new federal employment ceilings that will reduce the government's nondefense payroll by 33,000 this fiscal year and another 63,100 in fiscal 1982.

Most of the reductions will occur through attrition, Office of Management and Budget spokesman Edwin Dale said afterward, but in some agencies, which he did not name, "reductions in force" will be imposed, meaning some employes will be fired.

The personnel cuts from Carter administration projections will save $1.3 billion in two years, Reagan said in an opening statement to his second presidential news conference. The Carter administration forecasts put the full-time, permanent payroll at 2,111,000 next September and 2,132,000 the following year, according to Dale.

The permanent personnel ceilings will replace the hiring freeze Reagan ordered the day he took office, and will be part of the budget package he will send to Congress Tuesday.

Reagan mixed several jokes with his answers to reporters, but he also seemed occasionally defensive, disclaiming responsibility for two of his early decisions.

The Reagan administration brought the El Salvador crisis into the spotlight with a series of cries of alarm and pledges of action, but instead of seeking to take credit for the change in policy, he said: "I didn't start the El Salvador thing. I inherited it."

On El Salvador, his thrust appeared to be to minimize the dangers rather than sound a warning. "We don't foresee the need of any American troops," Reagan said twice. The 50-odd U.S. advisers there are not unusual, he said, because "we have such training squads in more than 30 countries today."

Asked about the possible danger to those advisers, Reagan said, "We can't, I'm sorry to say, make it riskfree, but we shall do our utmost to provide for their safety."

The president refused to say what the United States would do should the threatened right-wing coup take place in El Salvador, but he said such a coup "would be of the gravest concern to us."

A Reagan discussion of the dangers of El Salvador and fears that he might be more reckless than his predecessor concluded with a joke:

"I've been here more than six weeks now and haven't fired a shot."

The president also said he was only an inheritor of the complete decontrol of oil prices, a move he favored during his campaign and put into effect early in his administration.

When asked if he had any second thoughts about his decision in view of recent increases in gasoline prices, Reagan did not defend his action directly, but stressed that he had only advanced decontrol that was scheduled to take place at the end of this fiscal year. Part of the recent price increases, he said, are "due to the decontrol that had begun under the previous administration."

On the economy, the president said that even with the passage of his economic program, improvement would only begin to be seen by the end of fiscal 1982. "I hope that the public would understand this," Reagan said, "that one of the things that must be realized is we're not promising any instant cure."

Reagan conceded that his proposed personal income tax reduction of 10 percent a year for the next three years might be inflationary if people use their tax savings to pay bills and buy consumer goods. However, he drew a parallel between his proposals and the tax cuts of former president John F. Kennedy, and said there was a great increase in private saving and in investment following the Kennedy cuts.

He said he is not looking for any confrontation with Congress on his economic program and believes, despite recent Democratic opposition to his tax proposals, that there is "sufficient reason to believe that there is great bipartisan support for our program."

Reagan, sticking to his avowed policy of never tipping his hand on planned actions, refused to say whether he would veto a tax bill if it emerged from Congress with substantial changes from his proposals. Last week, Reagan told Rep. Henson Moore (R-La.) that he would consider a veto in those circumstances.

The president said he could not comment about the private group that is raising money to support the selling of his economic program because he has nothing to do with that effort. He named the man who has been leading that effort, Charles Z. Wick, as director of the International Communications Agency yesterday.

Reagan frequently greeted reporters' questions with quips. "Do you really want to?" he joked when a reported said, "I'd like to get back to El Salvador for a second."

After listening to a question that ended with an accusation, Reagan began his reply this way: "How can you say that about a sweet fellow like me?"

Twice, Reagan referred to his experiences as governor of California. He said his economic program would not injure the poor, and cited his experience with welfare reform in California.

Although 350,000 people disappeared from the state welfare rolls, he said, "We never had a single case of anyone suddenly appearing and saying, 'I am destitute. I have been cut off welfare.'" The president said that those cheating the system dropped off the rolls when they became afraid that the spotlight would fall on them.

"It is this theory that is behind what we are doing," he said.

Reagan called drug abuse "one of the gravest problems facing us internally in the United States." In California, he said, a program of sending former drug users to talk to young people proved effective.

"I envision whatever we can do at the national level to try and launch a campaign nationwide because I think we are running a risk of losing a great part of a whole generation if we don't, the president said.