The National Front for the Defense of the Constitution (FNDC) had called for fresh demonstrations in the capital Conakry on Monday and September 4, after accusing junta forces of killing two teenagers during previous protests.
But in a statement sent to AFP on Saturday, the FNDC said it had "complied with a request from the heads of the Economic Community of West African States and Guinea Christians to suspend the peaceful citizen demonstrations".
The September 4 protest would have fallen on a Sunday, "a day of prayer for our Christian compatriots."
The FNDC said it wanted "to give yet another chance to ECOWAS mediation so that it can find a way out of the Guinean crisis maintained by the military junta."
It was not suspending its call for nationwide protests on September 5, however.
The ECOWAS point-man for Guinea, former Benin president Thomas Boni Yayi, has been holding talks in the country since August 21.
The FNDC, a coalition of political parties, trade unions and civil society organizations, was banned by the junta in August.
The alliance staged rallies on July 28 and 29 in which five people were killed. Two teenagers, aged 17 and 19, were shot dead during protests it called for on August 17, which were banned by the junta.
The FNDC, relatives and neighbors accused junta leader Mamady Doumbouya's forces of having killed the two boys, charges the junta has denied.
The poor but mineral-rich state has been ruled by the military since a coup last September that ousted president Alpha Conde, in power since 2010.
In May, the junta banned all protests and on August 6 decreed the dissolution of the FNDC.
The FNDC spearheaded protests against Conde while he was in power, fiercely opposing his bid for a third term that it said was unconstitutional. The demonstrations were often brutally repressed.
Since the coup, the group has turned its focus on the junta, progressively amplifying its concern over human rights and the pace of return to civilian rule.