The nation's organized home building industry pledged yesterday to hold the line on profits for the next six months.

At the same time, the Commerce Department reported that new housing construction during April reached the highest level of 1978.

Housing starts were 15.3 percent higher than a year earlier and permits for future construction advanced 5.9 percent from the level of 1977 - which was a record year for new single-family housing.

A pledge to hold down housing price increases was announced by Ernest A. Becker, president of the National Association of Home Builders. "The only price increases will be the actual increased costs of doing business," said Becker, following a NAHB board meeting here.

A formal resolution about home prices was said to be an effort to show leadership in the fight against inflation but the NAHB initiative reportedly was not discussed in advance with the White House.

President Carter's inflation counselor Robert Strauss commented: "Some aspects of this are positive but some are troublesome. I welcome any effort the home builders might make and I look forward to meeting with them to better define their proposed action. If placed in a constructive posture, their efforts could be of value."

Strauss would not elaborate on what might be "troublesome" but a spokeswoman for the Council on Wage and Price Stability indicated that other home builder resolutions on immediate budget balancing and no tax cut would hurt the economy.

NAHB president Becker conceded yesterday that not all of the builders in his 102,000-member group could be expected to comply with the position taken by their leaders.

Even the six-month time period was not part of an official NAHB resolution, according to Becker. but he said that long a period should provide evidence whether other manufacturers of products, governments and unions are willing to take actions to hold down other prices.

The promise of a major effort to hold down builder dollar profits to that of the previous six months came after the 1,300-member NAHB board of directors expressed concern about rising interest rates and the effects of inflation on housing.

After almost 2 million housing starts in 1977, the level of new residential construction has continued strong this year. The government report yesterday showed that new homes and apartments were built at an annual rate of 2,19 million units in April. In April, actual starts tabulated by the federal government tataled 199,800, an increase over the 182,400 starts in April, 1977 and a 15 per cent increase over the 173,200 starts in March, 1978.

NAHB economist Michael Sumichrast, who has predicted a downturn in housing starts later this year for a total between 1!7 and 1.8 million in 1978, conceded that the starts in the first four months of thie year have been "excellent". The 562,900 starts in the first third of 1978 exceeded starts in the same period last year, when 549,600 were made.

At a press conference, Becker also said that NAHB is also "calling on local and state governments and their unions to hold off salary increases." NAHB directors supported a resolution urging an "immediate freeze on federal civil service hiring until a 10 percent reduction in the number of civil service employees is accomplished through attrition."

In addition to being worried about the effect of rising mortgage interest rates on home buyer demand, builders also are concerned about the start of the nation. Most of the nation's new housing is built with non-union labor but Becker said he would like to meet with unions, other industries and government to discuss ways of holding down costs and prices.

The NAHB also passed a resolution calling for a rollback of the higher interest rate certificates of deposits paid by savings institutions that make mortgage loans - approved by U.S. agencies only last week. The home builders also opposed "involvement by savings and loan associations in the form of actual building and development," directly or indirectly.

Robert D. Bannister, 34, was named by NAHB senior vice president for governmental affairs. He had been deputy director of governmental affairs with the National Association of Realtors hers.

Wayne Stetson will become the NAHB vice president for conventions and meetings.

Alan R. Trellis announced his resignation as director of technical services for NAHB. He now is building houses in Columbia, Md., where he lives.