President Reagan today clashed with New York Gov. Mario M. Cuomo (D) over the governor's criticism that Reagan's tax plan would hurt the middle class.

Reagan fired back "Balderdash!" to a claim last Sunday by Cuomo that Reagan's tax revision plan would penalize middle-class Americans while benefiting the wealthy and the poor. Cuomo made the remark on NBC's "Meet the Press."

"I finished watching that show on the ceiling, looking down," the president said today, describing his anger at the comment.

Cuomo said later today in an interview in Washington, "It's flattering that he turned to my channel and never turned it off even from the ceiling." Cuomo added that Reagan "doesn't differ with me, he differs with [New York Sen.] Al D'Amato, with [New York Comptroller Edward V.] Ned Regan, and in the last poll, with 70 percent of the American people."

Cuomo, a potential Democratic presidential aspirant, has been leading the opposition to Reagan's proposal to eliminate the deduction for state and local taxes, which would hurt taxpayers in high-tax states such as New York.

Responding to Cuomo's criticism that the middle class would be hit the hardest, Reagan said today in a speech to senior citizens here, "If I may use a word that people our age will remember, 'Balderdash!' There are some earthier words, but 'balderdash' will have to do.

"As I've said, we intend to cut personal income tax rates, and raise deductions and exemptions for the family," Reagan said. "This means that every group in America will be better off -- and anybody who tells you otherwise doesn't understand or deliberately doesn't want to understand."

Presidential spokesman Larry Speakes told reporters, "You don't think Mario is going to be mad, do you? I hope not."

The president cited what he called "an important new study" by New York Comptroller Regan, who is the highest elected GOP state official. "That study concludes that, under our proposal, taxpayers in that state would save $588 million a year," Reagan said. "And that's the point: if individuals are better off, states are better off, and America is better off."

However, the president selectively quoted from the study. A spokesman for Regan, Marvin Nailor, said today the study found Reagan's tax plan would cost New York taxpayers $2.4 billion in the first year. The chief reason for this, he said, is the six-month delay between the elimination of the state and local deduction and the scheduled phase-in of lower tax rates. The $588 million gain for New York would come in 1987, once the plan is fully implemented, he said.

Although the president didn't mention it today, the study also said eliminating the state and local deduction would "have a very harmful effect" on New York City and state. Moreover, the study reported that New Yorkers would get a 1.1 percent federal income tax cut, as compared to 7 percent nationwide when the plan is fully phased in.

Cuomo said today that Reagan was "blatantly mistaken" and had "distorted substantially the reality" of how his plan would affect New York. Cuomo said Comptroller Regan had joined him in a news conference last week to reiterate their opposition to eliminating the state and local deduction.

Reagan also sounded a defensive note today on the subject of Social Security.

"I've been accused -- oh boy, have I been accused -- of wanting to tamper with Social Security more times than I've had birthdays, and that's getting to be a pretty big number," he said. "Well, it just ain't so."

"As long ago as the 1976 campaign, I was saying that correcting the problems of Social Security must be done without reducing the benefits for those receiving them. I want you to know that nothing in our tax plan would affect your Social Security checks in any way -- period."

Reagan did not mention that twice over the last nine months he endorsed plans to reduce Social Security cost-of-living adjustments, which he promised not to alter in the 1984 campaign. The second proposal, to delay inflation adjustments one year, was approved by the Senate but Reagan later abandoned support for it.