The White House is asking defense contractors to give President Carter an assist in persuading the Senate to approve the strategic arms LIMITATION TREATY (SALT II).

Several executives of firms that produce weapons for the government told the Washington Post they had been called over the last few weeks by White House staff members.

Anne Wexler, head of the White House pulic liaison office, confirmed that defense contractors are among the businesses her staff had called on behalf of SALT II.

She termed the calls "very routine." She answered "absolutely not" when asked if there was any White House implication that future defense contracts would be linked to SALT II support.

Wexler said the calls being made to defense contractors and other businesses are in the "survey" stage to be followed later by White House briefings on the arms treaty.

Most executives contacted about SALT II, Wexler said, told the White House staffer who called them that they would have to check with their top management beofre giving the firm's stand on the treaty.

One aerospace executive said he was called by Judy Mercado, a White House fellow working for Wexler, and asked if his firm, which is one of the nation's top defense contractors, would get behind the treaty.

"They want us to contact our congressional delegation," he said. "I told them I would have to check with my top management and report back. They do this kind of thing all the time, I considered it routine."

Mercado said she called defense contractors, as well as others, on behalf of SALT II. She replied, "I would rather not comment" when asked what she had requested defense contractors to do.

"Of course the intent is to help us with SALT," Wexler said of the phone conversations with defense contractors. Mercado was "doing nothing improper" in making those calls.

Some defense executives told The Post that the calls seemed to be White House pressure to support the treaty.

"They really shouldn't feel that way, Wexler replied when told about this interpretation. Some business executives will be for the treaty, some will be against it, she said.

She put the Carter administration's SALT II lobbying in the same category as the earlier effort to make the case to the business community for the Panama Canal treaties.