The assault comes following the expiry of a deadline set by the UAE for the Houthis, who hold Sanaa, to hand over the port that has been under their control for years.
The UN said 600,000 people live in and around Hodeidah, and "as many as 250,000 people may lose everything - even their lives" in an assault.
Local military sources said hundreds of Yemeni fighters as well as tanks and military supplies from the UAE arrived on Monday to reinforce troops, including Emiratis and Sudanese, in al-Durayhmi, a rural area 10 km (6.21 miles) south of Hodeidah.
Emirati-led troops have advanced along the southwestern coast to the outskirts of Hodeidah under a coalition strategy to box in the Houthis in the capital Sanaa and choke off their supply lines to force them to the negotiating table.
"The liberation of Hodeidah port is a turning point in our struggle to recapture Yemen from the militias that hijacked it to serve foreign agendas", the exiled government said in a separate statement carried by state-run Yemeni media.
The Arab coalition has repeatedly said that it will protect Al Hodeidah's lifeline and seek to secure the lives of civilians.
The Houthis deny they are Iranian pawns and say their revolt aims to target corruption and defend Yemen from invaders.
Khalid bin Salman, Saudi Arabia's ambassador to the U.S., noted on Wednesday that the Houthis kept obstructing mediation efforts and rejecting a plan to hand over Al Hodeidah to the UN.
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"We have had more than 30 airstrikes within 30 minutes this morning around the city".
The UAE foreign ministry and government communication office did not immediately respond to Reuters requests for comment.
The United Nations fears the assault could drastically worsen already desperate conditions in the region's poorest country.
The UN and International Committee of the Red Cross said on Wednesday that all parties in Yemen's war must protect civilians.
"It's providing any intel, or anything we can give to show no-fire areas where there are civilians, where there's mosques, hospitals, that sort of thing - (and) aerial refueling, so nobody feels like I've got to drop the bomb and get back now", he said.
The renewed push on Hodeidah comes amid increased tensions between Saudi Arabia and arch-foe Iran after the United States withdrew last month from an worldwide nuclear agreement with Tehran, a move hailed by Riyadh and Abu Dhabi.
Riyadh says the Houthis use the port to smuggle in Iranian-made weapons, including missiles that have targeted Saudi cities.
Houthi-run Al Masirah TV said two missiles struck the barge, but there was no immediate confirmation from the coalition.
Yemen lies beside the southern mouth of the Red Sea, one of the most important trade routes in the world for oil tankers, which pass near Yemen's shores while heading from the Middle East through the Suez Canal to Europe.