Senate Majority Leader Bob Dole charged that House Democratic leaders are deliberately blocking final action on a $100-million package for aid to the contras fighting Nicaragua's Sandinista government. A top aide to House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) said the Kansas Republican's charge was "absurd." Meanwhile, President Reagan again urged Congress to take final action, saying that the contras are "clinging to our promise of assistance."