The meeting between Ansarullah chief Abdelmalek al-Huthi and Al-Islah party delegates took place late Thursday in Huthi's northern stronghold of Saada, the Shiite militants said on the Internet.
The rivalry has intensified since Ansarullah moved beyond Sanaa and also seized territory in central and western Yemen.
The Shiite advance has slowed in the face of a counter-offensive by Sunni tribes close to Al-Islah and Al-Qaeda, plunging the country into an unprecedented political crisis.
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Al-Islah issued a statement saying the two sides "expressed willingness to cooperate and coexist in accordance with the precepts of Islam advocating brotherhood, love and peace".
The statement said that because of "the dangers threatening Yemen, it was agreed to continue contacts to end the tension and contain the impact of recent events".
An Al-Islah official told AFP the two sides were "negotiating a draft agreement" that, according to a source close to the talks, was meant to "defuse the risk of sectarian conflict" in Yemen.
Support for Al-Islah, previously a main political force with its tribal alliances, has wavered since president Ali Abdullah Saleh quit in early 2012 after a year of bloody protests.