President Carter warmly welcomed Secretary of State Cyrus R. Vance home from his Asian trip yesterday, but let it be known that full diplomatic recognition of China "is undoubtedly going to be well into the future."

Carter, greeting Vance at Andrews Air Force Base, called the Secretary of State's seven-day visit to China and Japan "a very important step forward in our ultimate goal of normalizing relations" with the Chinese.

But both in his welcoming remarks and in a transcript of an interview with reporters released yesterday, the President took special care to point out that Vance's trip was an "exploratory" one with deliberately limited goals.

The language he used gave him great flexibility on the recognition issue and appeared to be designed to allay suspicions that the United States would abandon its long-standing ties with Taiwan.

Vance's reports from Peking were "very encouraging," Carter said in the interview, which also touched on the Panama Canal and the Mideast. "But we don not intend to act hastily. When we do make a decision about China, if we make one of recognition, it is undoubtedly going to be the best interest of our country."

Carter said he believed it was important to get acquainted with mainland China's new leadership and explore the terms under which normalized relations would take place if full "regocnition is not initiated."

In the same interview with visiting reporters, Carter warned that failure by the Senate to ratify the Panama Canal treaty would result in "very severe consequences" to relationships with Latin American nations.

Laying out a game plan to build public support for the treaty, the President said he intends to make a fireside chat to the nation soon on the issue and has begun inviting "key opinion-shapers from individual states" to the White House for briefings. The first of these briefings, with delegations from Kentucky and Mississippi, occurred on Tuesday.

He also said about 10 top Latin American leaders have agreed to come to Washington Sept. 7 to ratify the treaty and express their support for it.

Expectations of "new friendship, new trade opportunities and a new sense of commonality and equality" have built throughout Latin American as a result of the negotiations over the canal, Carter added.

"I think if those hopes were dashed . . . the consequences would be very severe," the President said.

The canal treaty and one guaranteeing the neutrality of the waterway to be signed by all Latin countries have raised a storm of protest among conservative groups both in and out of the Senate.

Recent polls have indicated that the administration faces an uphill fight in swinging enough votes to ensure passage of the treaties, and private organizations have launched a media campaign protesting the pacts.

Carter acknowledged that public support for the treaty is weak, but said, "If I can't sell the American people on the fact that the terms of the treaty are beneficial, then I will have a very difficult time selling it to the Senate. But I predict that the treaty will be ratified."

Sounding somewhat more pessimistic than in the past, Carter carefully chided Israel on its failure to come to terms with its Mideast neighbors. Without mentioning Israel by name, he said there is a "growing impatience" among other nations concerning the Mideast conflict.

Any nation "that proved to be intransigent or an obstacle to progress would suffer at least to some degree the condemnation of the rest of the world," he said.

By contrast, he noted that his administration had found a "much more compatible relationship" and a "much more flexible attitude" among Arab leaders.

Although he claimed to be hopeful that a Mideast settlement can be reached, Carter said "there is going to be a great deal of disillusionment on our part in the Middle East and around the world if some progress is not demonstrated within this year."

On the surface, Vance, who only two weeks ago returned from a fruitless trip to the Mideast, returned to Washington without visible achievement yesterday after the administration's first high-level contact with the new Chinese leadership.

He reported little in a brief press conference at Andrews, saying simply, "We had a good and useful trip to China."

He told reporters before leaving Japan that he thought China's leaders had a better understanding of U.S. views. But there was no indication that any progress toward normalizing relations had been made or that China had backed down from its demand for unconditional American disengagement from Taiwan.

Carter, in his meeting Friday with out-of-town newspaper editors and broadcasters, made it clear he intended to "honor our long-standing commitment so that the people in Taiwan could live in freedom."

He also tried to allay fears that the Panama Canal treaty would hurt the United States militarily, saying it "would greatly lessen the chance of violence and the need to defend the Panama Canal with force."

"The ownership of the canal is not nearly so important to me as the openess of the canal and its free access to all countries, as has been the case in the past without our having the right to defend under any circumstances, to operate it at the end of this century, and to have our own warships, in the case of an emergency, have power," he said.

Carter said he has talked with 50 or 60 senators since the treaty was completed, and he thinks he has persuaded many former opponents ofthe treaty to vote for it.