National Endowment for the Humanities chairman William Bennett said yesterday there are 10 grants that he recently approved but had wanted to reject.

"If things were otherwise, I would not have signed those grants," Bennett told the National Council on the Humanities, meeting here yesterday, "but I found promises had been made to the grantees" that they would be funded.

"Not only must a chairman keep his word, an agency must keep its word," Bennett said. "But if it hadn't been for agency propriety, I would not have signed them . . . I will not feel it incumbent upon myself to defend those grants."

Bennett has been NEH chairman for less than two months--confirmed by the Senate less than two weeks ago. Yesterday was the first time Bennett acted as chairman of the council, a presidentially appointed advisory body that reviews NEH grants after peer panels make recommendations but before the chairman signs them.

Bennett, who did not specify the proposals he found wanting, said he found a number of the 10 proposals "unsatisfactory on several grounds." He said they were:

* not really pertaining to the humanities;

* more political than humanistic;

* and "badly thought out and weakly described."

"I found some grants recommended by the previous chairman still not out of the system, and I asked for a review of those letters since I would have to sign them," Bennett said.

At the National Endowment for the Arts, NEH's sister agency, chairman Frank Hodsoll has similarly questioned the funding of certain proposals approved under the previous chairman and sent some already approved by peer review panels back for further review.

Bennett said he has problems with other grant proposals already approved by panels. "There are a number of proposals up for this council meeting that I've suggested we look at again, defer, get more staff discussion on," he said.

Among other business at yesterday's meeting was the official announcement of the 1982 Jefferson Lecturer and the discussion--in closed session--of who would be the Jefferson Lecturer for 1983. The Jefferson Lecture, which carries an honorarium of $10,000, has been delivered in past years by such noted figures as historian C. Vann Woodward and authors Barbara Tuchman and Saul Bellow. The 1982 lecturer will be Emily Townsend Vermeule, Harvard University classicist, archeologist and scholar of ancient Greek culture. Vermeule will give her lecture, "Greeks and Barbarians: The Classical Experience in the Larger World," here May 5.

Also at yesterday's meeting, Bennett introduced the new general counsel, Wendell Willkie, who replaces Joseph Schurman who retired last month. Willkie, 30, was an associate of the New York law firm, Simpson Thacher and Bartlett. He is the grandson of 1940 Republican presidential nominee Wendell Willkie.

At the National Endowment for the Arts, a new high-ranking staff appointment was announced yesterday as well. Robert Knisely, who has been in federal government for 16 years, was appointed deputy chairman for management. Knisely, who was most recently executive assistant to the director of ACTION, will have responsibility for budget, personnel, accounting, auditing, grants, contracts, civil rights and administrative services at the NEA.