"From now on, our country is free to purchase any sort of weapon we want from the world," Mohamud said in a declaration late Friday.
"Weapons in government hands will not pose threat to our people and to the world," the Somali leader added.
Friday's decision by the United Nations maintained the embargo on supplying weapons to the Islamist Al-Shabaab and other rebel groups.
The decision by the U.N. Security Council was a follow up to a 1992 imposition of an embargo on all arms deliveries to Somalia, though in recent years restrictions eased on sales to the central government.
"This decision comes at a very crucial time as a nation and people since we are in a war to eliminate Kharijites (Al-Shabaab) from the country," the National Intelligence and Security Agency said in a statement.
"It comes at a time when efforts are ongoing to form an army capable of taking on the general security responsibility of the country," added the statement.
After making initial gains, a government offensive launched in August 2022 against Al-Shabaab has stalled, leading to doubts about the Horn of Africa nation’s ability to quash the 16-year-old insurrection by the al-Qaida-linked group.
The army operations, in alliance with clan militias, has been supported by the African Union Transition Mission in Somalia, ATMIS in recapturing vast areas of the territory.
ATMIS was due to withdraw by the end of 2024, but the Somalian government has asked for a "technical pause" in the pullout. As a result, the mission is due to shrink from 17,626 soldiers now to 14,626 by the end of the year.