BEIRUT (Reuters) - Syria faced growing economic sanctions and condemnation over "gross human rights violations" on Monday, but President Bashar al-Assad showed no sign of buckling under international pressure to end his military crackdown on popular unrest. State television broadcast pro-Assad rallies "supporting national unity and rejecting foreign interference," after the Arab League imposed sanctions on Sunday. The European Union weighed in one day later, further tightening the financial screws on Damascus for its "brutality and unwillingness to change course." Assad's foreign minister Walid al-Moualem hit back, lambasting the Arab League for "a declaration of economic war" that he said had closed the door to resolving the crisis. "Sanctions are a two-way street," Moualem told a televised news conference. "I am not warning here, but we will defend the interests of our people ...." In Geneva, a United Nations commission of inquiry said Syrian military and security forces had committed crimes against humanity including murder, torture and rape, for which Assad and his government bore direct responsibility. It demanded an end to "gross human rights violations" and the release of those rounded up in mass arrests since March by Syrian forces quashing pro-democracy demonstrations. Over 3,500 people were killed in 8 months, the UN says. Syria's close trading partners Lebanon and Iraq rejected the Arab League measures, whose economic impact could be less severe than intended, analysts said. "We do not agree with these sanctions and we will not go along with them," said Lebanese Foreign Minister Adnan Mansour. The Arab League meanwhile appealed once more to Damascus, offering "a review of all of the measures" if Syria dropped its opposition to an Arab plan to end the crackdown. Anti-Assad activists in Syria said on Sunday that security forces had killed at least 24 civilians, many in a town north of Damascus that has become a focus for the protests. Others were killed in raids on towns in the province of Homs, they said. In an apparent political concession, which protesters have been demanding for months, Moualem said Syria planned to drop a constitutional clause which designates Assad's Baath Party as the leading party. The revised constitution foresees "multi-party" politics with "no place for discrimination between parties," he said.The Arab League sanctions hit banking, finance, investment and official travel but stop short of a full trade embargo. "The sanctions are still economic but if there is no movement on the part of Syria then we have a responsibility as human beings to stop the killings," said Sheikh Hamad bin Jassim al-Thani of Qatar, the League's point man on Syria.