West Germany plans to balance a call for a strong military defense with a reaffirmation of East-West detente at a June meeting here of NATO leaders, a government spokesman said yesterday.

A set of guidelines on security policy reflecting this balance was presented by Chancellor Helmut Schmidt to a Cabinet meeting and debated for more than three hours with leaders of Bonn's two coalition parties also attending, Washington Post correspondent Bradley Graham reported.

Reporting on the debate, government spokesman Kurt Becker said Schmidt had not been contradicted, suggesting that the release of the guidelines now is intended also for domestic purposes--namely to rally Germany's political leadership behind an evenhanded policy Schmidt can use to fend off an expected left-wing challenge at a national congress of his Social Democratic Party in April.

West German officials apparently hope that the two-track approach of the guidelines will blunt any move by the Reagan administration for a more one-sided statement of principles at the June summit.

That meeting of the heads of NATO's 15 countries--the first such gathering since 1978--is regarded by Western officials as critical if the alliance is to smooth over deep U.S.-European differences in approach to the Soviets.