The assistance was offered when Singh spoke to the Chief Ministers of these states.
The Prime Minister also conveyed his condolences and sympathy to those affected by rain and floods in these states.
The flood in Assam has affected more than two lakh people in 240 villages.
In Andhra Pradesh, 41 people were killed as heavy rains lashed several parts of the state. The rainfall caused extensive damage and disrupted rail and road traffic.
At least 10 people have also been killed in rain and landslides.