"Don't bet on the UN whose role conforms to American policy," Abdulmalik al-Huthi said in a speech yesterday for the Muslim celebration of Mawlid marking the Prophet Mohammed's birthday.
"We have no choice but to resist... Until our people achieve their freedom and independence," he added.
The defiant stance comes after Yemen's warring parties on Sunday concluded UN-sponsored peace talks in Switzerland with no major breakthrough, but agreed to meet again on January 14.
The Huthis, a Shiite minority from Yemen's north, seized the capital Sanaa last year and then advanced south to the second city of Aden, forcing President Abedrabbo Mansour Hadi to flee to Saudi Arabia.
Following territorial gains by loyalist troops backed by a Saudi-led coalition, Hadi returned to Aden in November after six months in exile.
The conflict has escalated dramatically since Saudi-led air strikes against the rebels began in March, with nearly 6,000 people killed according to UN figures.