Philippine President Ferdinand Marcos warned opposition groups Sunday that his administration had discarded its policy of ''maximum tolerance'' in dealing with antigovernment violence and would meet force with force. Mr. Marcos also said he was prepared to listen to the recommendations of a ''national reconciliation council'' proposed by Roman Catholic Jaime Cardinal Sin.
Police and the military conducted random checks for guns, explosives, and other weapons in Manila, the scene of violent street demonstrations last week demanding Marcos's resignation. Despite the government's announcement banning unauthorized demonstrations, opposition sources said that a series of protest marches are planned for this week. In Davao, 600 miles south of Manila, 13 people were killed Saturday in a grenade attack attributed by police to the outlawed New People's Army.