NEW : Unrest reported in Taiz , Sanaa and Hodeida . The Yemeni government has been under pressure from the Houthi rebels for months to step up its fight against them. UNICEF voices concern over children 's deaths .
NEW : Unrest reported in Taiz , Sanaa and Hodeida . The U.N. Security Council discusses Yemen . UNICEF voices concern over children 's deaths .