Ban Ki-moon, the UN secretary general, said dialogue was necessary and called on Guinea’s security forces to "exercise maximum restraint".
Conte sent in the army to end rioting and looting that accompanied the relaunch of a general strike by unions on Monday after he named an Eugene Camara, a close ally, as prime minister.
Unions said Camara's appointment violated previous agreements.
"Camara could resign but that wouldn't be enough. People really want rid of Conte," said one western diplomat in Conakry.
Sporadic gunfire was heard in some neighbourhoods of the capital Conakry.
Residents said heavily armed soldiers and police broke up protests, cleared barricades and rounded up curfew breakers.
The martial law measures restricted civilians to their homes for all but four hours of the day, and gave the armed forces powers to detain suspects.
The military also has control over broadcasting, the press and communications.
Residents rushed to market stalls that opened after 4 pm local time, as supplies of basic foods like bread and rice ran low.
"I went to the market but came back very quickly. It's not sensible to stay outside when you can hear gunfire," said Maimouna Keita, a resident of Conakry's Taouyah neighbourhood.
The martial law measures have heaped further hardship on Guinea's nearly 10 million population, most of whom live in poverty.
The UN World Food Programme suspended operations after three food warehouses were looted at the weekend by residents.