Residents said they had not seen any extra security in Aden, where armed forces loyal to Hadi's government, the Southern Transitional Council and the Saudi-led coalition are all present.
But witnesses said government forces were deployed on roads leading to the presidential palace in the Maasheeq area, where the government is based.
Witnesses also said that thousands of people had arrived in Aden from across the former South Yemen, which merged with North Yemen in 1990, to participate in a gathering expected to be held on Sunday.
Yemen has been torn by armed conflict since the Houthis captured the capital Sanaa in 2014 before they marched south towards Aden the following year in a military campaign that culminated with Hadi fleeing into exile.
The Saudi-led coalition that entered the war after Hadi sought refuge in Saudi Arabia in March 2015 has helped local fighters free Aden from Houthi control and made other military gains in different parts of the country. But the Houthis continue to control most of northern Yemen, including Sanaa.
The Southern Transitional Council was formed last year to push for a split between the former South Yemen and North Yemen.
Southern forces have previously clashed with Hadi supporters, including members of the Islamist Islah party, over control of strategic areas, such as Aden airport and oil facilities.
