Armed men kill 30 villagers in Mali attacks, say local officials
That was a reversal from Wednesday when protest leaders had said that Keita's resignation would no longer be a condition for talks.
Earlier, Dicko said he had hoped to find a solution to the standoff after meeting the president.
"My role as an imam, as I have said, obliges me to be someone who always considers peace as being essential: peace in our country, the sub-region and in the world".
The slow pace of political reform, a flagging economy, a lack of funding for public services and schools and a widely shared perception of government corruption have fed anti-Keita sentiment.
Last month's protests followed demonstrations in May over the results of March's long-delayed parliamentary elections - which Keita's party won - as well as over coronavirus restrictions.
The 75-year-old president has taken a conciliatory stance since the demonstrations began, mooting a national unity government in a 14 June address to the nation. Protest leaders rejected that offer.
One of the poorest countries in the world, Mali has been engulfed in conflict since a jihadist insurgency emerged in the north in 2012 and spread to the fragile centre of the country in 2015, as well as to neighbouring Burkina Faso and Niger.