A peaceful end "cannot be reached unless a balance on the ground is achieved, in order to force the regime to sit down to talks," he told ministers in Doha for a "Friends of Syria" gathering.
"Getting arms and using them could be the only way to achieve peace," he added.
Foreign ministers of governments that support the Syrian opposition met in Qatar today for talks on boosting their assistance after rebels hailed recent deliveries of new weapons.
However, Sheikh Hamad also voiced support for the holding of a peace conference in Geneva proposed jointly by Washington and Moscow.
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"Of course, we support holding a Geneva conference II to achieve a peaceful power transition through the formation of a transitional government that would enjoy full powers," he said.
But he insisted "no role would be for Bashar al-Assad and aides with bloodstained hands" in the future government.
"The regime will work endlessly to prevent the convening of the conference or to make sure it fails, because... It is only interested in staying in power, even if that costs one million dead, millions of displaced and refugees, and the destruction of Syria and its (territorial) partition," he said.