Gachagua also said Mombasa "has the worst drainage system which worsened the floods after heavy rains".
"Nassir should borrow a leaf from Nairobi that has employed the youth to unclog its drainage system. Instead of sitting and complaining, he should buy food for his people because he has money," he said.
But Nassir has been distributing food to families affected by floods since last week.
Gachagua said some counties have bought food to supplement efforts by the national government to feed families affected by floods.
"Let Nassir buy food and we will give him military helicopters. Other countries like Wajir, Mandera, and Garisa have done so. This is not the problem for the national government alone," he said.
Yesterday, the deputy president distributed relief food to more than 500 families in Barawa village, Kisauni constituency.
Gachagua called on counties to clear waterways and drainage systems while enhancing financial, technical, and logistical support.
Last week, floods at the Coast claimed 12 lives, causing destruction of property of an unknown value. Thousands of families were displaced in Mombasa, Kilifi, Kwale, Tana River, Taita Taveta, and Lamu counties.
Government officials reported several missing individuals, with over 20,000 people displaced. Last week, Coast Regional Coordinator Rodah Onyancha said that the most affected counties are Tana River and Mombasa.
In Tana River, more than 5,000 families were displaced after River Tana burst its banks, leading hundreds of residents to relocate to Gamba.
Ms Onyancha reported that heavy rains and floods have impacted 3,892 families in Mombasa, with at least 300 families lacking shelter as their houses were either submerged or swept away by the floods.