The City Council last night directed the Cambridge civil defense director to cease planning for the evacuation of the city in the event of a nuclear attack and instead devote his efforts to campaigning for the ratification of the SALT II arms limitation treaty and nuclear disarmament.

Following a three-hour public hearing last week, when area scientists ridiculed the notion that evacuating the city might save the lives of Cambridge residents, two councilors, Saundra Graham and David Wylie, addressed the issue at last night's session.

Graham's motion asks the state civil defense department to prepare a pamphlet warning of the dangers of nuclear devastation and to "conduct a program through all the media urging the citizens of Massachusetts to communicate to their Representatives in Congress and the Legislature the necessity of continuing negotiations with foreign powers to resurrect the SALT II talks."

The alternative, Graham warned, was the "irrevocable damage to our hemisphere and our world which would result from nuclear warfare."

Wylie's order contended that last week's hearing proved "that the sole means of protecting Cambridge citizens from nuclear warfare would be for nations with nuclear arms to destroy those arms and renounce thair use."

Wylie's order asked the city manager to "hold in abeyance further distribution" of the evacuation plan presented to the council last week. That plan calls for Cambridge residents to repair to Greenfield, in the western part of the state, in any nuclear "crisis."

Instead of the evacuation plans, Wylie called for the distribution of a publication detailing why "no step short of nuclear disarmament by all nations could protect Cambridge citizens."

"I think it will be a first," Wylie said, adding that the success of the project will "depend on the public interest we get."

National media exposure might result from the plan, and that in turn would "put the federal government in an interesting position. Either they could convince us that our approach was unsound or witness other cities starting to do this same thing," Wylie said.

State and city civil defense officials were unavailable for comment.