Robert H. Mendelsohn, whose nomination as an assistant secretary of the interior was withdrawn last November because of alleged violations of California election laws, was appointed yesterday to oversee the Interior Department's urban, manpower and youth programs.

Mendelsohn's new $47,500-a-year position carries the title "assistant to the secretary" and does not require Senate confirmation.

Interior Secretary Cecil D. Andrus said he gave Mendelsohn the job because the former San Francisco city supervisor had been "vindicated" and because "We want to put Bob Mendelsohn's talents and energies to work for the Interior Department without further delay."

"I said that I was cnfident Bob would be vindicated, and I think it's time to put all of that controversy behind us and move ahead," Andrus said."

President Carter had nominated Mendelsohn to serve as assistant interior secretary for policy budget and administration - a position that would have paid $50,000. Last Nov. 11, Andrus reluctantly requested that the nominated be withdrawn because of charges by the California Fair Political Practices Commission that Mendelsohn and his campaign committee violated financial disclosuer laws in a 1974 race for state controller.

The commission's suit was dismissed "with prejudice" last month by a San Francisco Superior Court. The campaign committee paid the commission $5,000 for incorrectly reporting contributions, and the commission, in return, said it had no concrete evidence that Mendelsohn knew about a $26,500 contribution illegally made to his campaign.

"The secretary carefully examined the court's action and decided that it vindicated me," Mendelsohn said yesterday. "I am very pleased about that - very happy," he said.

In his new position, Mendelsohn will be responsible for carrying out Carter's directions to the Interior Department to expand urbanparks and recreational facilities.

He also will handle Interior's role in overseeing $180 million worth of programs - the Job Corps, Youth Conservation Corps and the Young Adult Conservation Corps are examples - in the department's Office of Manpower and Youth Activity.

Mendelsohn, 40, a District of Columbia native, said he believes his background as a San Francisco city administrator and urban affairs activist will help him fulfill his duties.

"I think the secretary felt that I was in a unique position to do this job . . . It gives me a chance to be very valuable to the administration and to the cities," he said.

Andrus said yesterday that he still must find a "permanent appointee to be assistant secretary for policy, budget and administration." He implied that he would have chosen Mendelsohn again, were it not for the prospects of a long, probably unsuccessful, battle for Senate conformation.

Andrus said he has made another recommendation to President Carter for the assistant secretary's post, and said Carter would make his own announcement "in due time."