By Maya Gebeily and Ahmed TolbaBEIRUT, April 3 (Reuters) - Israel pounded Beirut with airstrikes on Friday that the military said had targeted militant "infrastructure" in Lebanon's capital, as the U.S. warned that Iran may target universities in the country as the Middle East war rages.Israel has invaded southern Lebanon and pledged to raze all Lebanese villages in the border area in a fight against Iran-backed Hezbollah militants that has become the most violent spillover of the U.S.-Israeli w...