President Carter, beginning a two-day political swing through New England, appealed yesterday for support for his tax cut proposals and strongly defended the administration's proposed Middle East arms sales.

At a nationally televised news conference, Carter predicted that Congress will approve the arms sales and said he did not believe that supplying both Israel and some of its Arab rivals with warplanes would increase the threat of war in the Middle East.

The president arrived in Rhode Island on the first leg of a trip in which he was to campaign for three Democratic senators facing re-election challenges this year.

Carter opened the news conference with a lengthly statement, expressing optimism on the outcome of coal strike negotiations and plugging for passage of his tax proposals.

Contending that the tax cuts would mean 1 million new jobs - a particularly sensitive subject in New England where unemployment runs high - the president said the tax cuts will not be effective unless they are accompanied by passage of the tax revisions he also has proposed.

He singled out for criticism two tax breaks now afforded to corporations, calling them "giveaways" that "cost America, and particularly New England, jobs."

One of these provisions allows corporations to defer taxes on their foreign profites until the money is returned to the United States. The other, known as DISC, in effect allows corporations to defer indefinitely taxes on half their export profits.

"As for the famous three-martini lunch," the president said in reference to one of his controversial tax revision proposals, "I don't care how many martinis anyone has with lunch, but I am concerned about who picks up the check.

"I don't think a relatively small minority has some sort of divine right to have expensive meals, free theater tickets, country club dues, sporting event tickets paid for by heavier taxes on everybody else."

Part of the administration's tax revision program would limit deductions allowed for such business expenses as lunches and entertainment.

Middle East arms sales was the only foreign policy topic to come up duing the news conference. Earlier this week, the administration asked Congress to approve the sale of F15 fighter planes to Israel and Saudi Arabia and short-range F5E fighter planes to Egypt. The F15, the most sophisticated plane in the U.S. arsenal, has been sold to Israel but never to an Arab nation. Nor has the United States sold warplanes to Egypt in the past.

The proposed sale, and its timing in the midst of the Egyptian-Israeli peace negotiations, have provoked sharp criticism on Capitol Hill.

Carter called the timing of the sale "proper" and referred to each of the three nations as "one of our closest allies and staunchest friends."

Regarding the first proposed sales of American warplanes to Egypt, long one of Israel's most bitter enemies until the recent Egyptian peace initiative, the president said of the F5Es, "I don't believe there is any danger of this relatively short-range and not advanced fighter causing a disruption in the peace between Egypt and Israel."

During the news conference, Carter also said that arms sales this year will be less than last year, one of his major objectives. But that claim is based on a technicality that the president did not mention. Actually, total American arms sales this year will be about $2 billion more than last year. Arms sales to countries other than NATO allies, Japan, Australia and New Zealand will be slightly less this year.

This was the first of several "regional" news conferences the White House plans this year and was open to reporters from throughout New England as well as the traveilng White House press corps. Not surprisingly, several of the questions dealt with local issues, particularly the economic impact of the winter storms.

The president noted that federal aid is already being provided to states hit by the storms. But he said it is up to the states to decide whether unemployment compensation funds should be used to make up for wages lost because of the storms.

On other topics, the president:

Defended the proposed settlement of the Maine Indians' land claims, under which the Indians would receive access to 300,000 acres of privately owned land, a lump sum payment of $25 million from the federal government and $1.7 million a year for 15 years from the state government. In return, the Indians would relinquish pending claims on 12 million acres.

Endorsed the right of the citizens of each state to decide for themselves, for example through referenda, how much they want to depend on nuclear power plants for energy.

Defended once again his appointment of U.S. attorneys, saying he has sought to retain those prosecutors "who are doing a good job."

Said he still hopes to achieve his goal of balancing the federal budget by 1981, although most administration officials have now given up on that target.

Before the news conference, Carter visited a group health facility to demonstrate his support for health maintenance organizations, which provide care on a set-fee, pre-paid basis.

The president arrived in Rhode Island early yesterday afternoon. He was accompanied from Washington by Sen. Claiborne Pell (D-R.I.) and Sen. William Hathaway (D-Maine) and former Maine governor and former Democratic Party chairman Kenneth Curtis.

Carter's New England swing was to be a mixture of official business and politics.

In Rhode Island yesterday afternoon he attended a fund-raising reception for Pell.

Last night he was to go to a fund-raising reception for Hathawoy in Bangor.

Today the president is scheduled to fly to Nashua, N.H., to answer questions from high school students and aid the re-election campaign of a third Democratic senator, Thomas J. McIntyre.

White House officials estimated that 75 percent of the trip would be taken up with official activities and that 75 percent of the cost would be paid by the government. The remainder of the expenses will be paid by the Democratic National Committee.

This is the first time Carter has gone on the road specifically to help the re-election bids of Democratic members of Congress. According to White House officials, many more such political campaign trips can be expected in the months leading up to the November congressional elections.

The president arrived in Rhode Island in pleasant winter weather with the temperature in the high 30s. Although the streets around Providence and Cranston were clear; hugh piles of cleared snow provided evidence of the storms that have battered New England in recent weeks.

Before he left Washington, Carter declared Rhode Island and New Hampshire major disaster areas, making storm victims in the two states eligible for additional federal aid.

Last night is Bangor, the president stayed in the home of Robert and Laura Murray. He is an appliance salesman, a former county Democratic chairman and an early Carter supporter in the 1976 campaign.