Some of the politicians attending Monday's meeting with President Mohammed Morsi appeared unaware it was being carried live on TV. Morsi did not directly react to the suggestions.
Morsi called the meeting to review the impact of Ethiopia's dam on Egypt's share of the Nile's water.
Younis Makhyoun, leader of an ultraconservative Islamist party, said Egypt should back rebels in Ethiopia or, as a last resort, destroy the dam. Liberal politician Ayman Nour proposed spreading rumors about Egypt obtaining advanced warplanes to scare the Ethiopians.
Egypt has in the past threatened to go to war to preserve its water share.