(CNN) -- Iran's foreign minister Tuesday called on Yemen's neighbors to stay out of the conflict between Yemeni forces and Shiite Muslim rebels, while Yemen said it had seized an Iranian ship near its territorial waters.

Manouchehr Mottaki told reporters in Tehran that Shiite-dominated Iran has expressed its concern for Yemen's "national unity and territorial integrity," the state-run Press TV network reported.

"We strongly advise regional and neighboring states not to interfere in Yemen's internal affairs and try to restore peace and stability to the state," Mottaki said, adding, "Those who choose to fuel the flames of conflict must know that the fire will reach them."

Battles between Yemeni government forces and the Shiite Houthi rebel movement have raged intermittently for five years in northern Yemen, where government troops launched a new offensive in late summer. The conflict is considered to be separatist and sectarian, pitting the Houthi against the country's Sunni majority.

Saudi Arabia, Yemen's northern neighbor, turned its air force against suspected Houthi rebels last week. The Saudi government said an armed group had infiltrated into its territory and fired on border guards, leaving three members of the Saudi security forces dead and 15 wounded before the airstrikes pushed them back.

The Houthi claimed the airstrikes occurred within Yemeni territory, a claim both the Saudi and Yemeni governments denied. Meanwhile, Yemen has accused Iran of supporting the rebels.

A Yemeni government official, speaking on condition of anonymity because he was not authorized to speak publicly on the issue, told CNN that Yemen's navy was "on the highest state of alert" and watching for any possible smuggling of weapons to the Houthi.

The official said an Iranian boat was captured near Yemeni and Saudi territorial waters last week and was being towed to the Yemeni navy's headquarters at Hudeidah, on the Red Sea.

The persistent fighting has raised concerns that Yemen -- where U.S. officials say al Qaeda is attempting to establish a new foothold in the region -- could be the stage for a proxy struggle between Iran and the Sunni-led Saudi monarchy. But the Yemeni official said the conflict in his country "is not a sectarian war."

"The main reason for fighting this group is that it's up in arms in rebellion against Yemen's government and it is challenging the legitimacy of Yemen's central government in Sanaa," he said. "The constitution of Yemen gives the government the right to defend the sovereignty and unity of Yemen. The leadership of the insurgency has a sectarian ideology, but that doesn't mean Yemen is involved in a sectarian battle."