The next protest on May 2 would be confined to the capital Nairobi, Azimio has announced.
"Today we have come to the conclusion that as we had feared, the commitment is lacking on the part of Kenya Kwanza," Azimio said in a statement on Monday, referring to Ruto's ruling Kenya Kwanza (Kenya First) party.
Thousands had taken to the streets in three marches which were marred by clashes between protesters and police. Rights groups called for calm, fearing an eruption of ethnically charged violence.
Opposition leader Raila Odinga halted nationwide demonstrations in early April after an appeal from President William Ruto, who agreed to talks and to reform the election commission - one of the opposition's main demands.
On Sunday, Ruto condemned Odinga's threats to resume protests and asked Azimio to give him time to turn around the economy.
The protesters have accused Ruto of mismanagement, while his supporters have accused Odinga of using anger over rising prices, a global phenomenon, to press for political concessions and a possible role in government.
The government has also insisted last year's national elections were fair.
Azimio said it remained committed to dialogue, but it accused the government of failing to bring down the cost of flour, fuel, electricity and school fees and objected to the make-up of Kenya Kwanza's negotiating team.