Tanzania left Comesa in September 2000.
The country is instead a member of the Southern Africa Development Community economic bloc and joined the East African Community (EAC) customs union in 2005.
Kenya is also a member of the EAC customs union and worries that there will be "inherent contradictions" if it is part of a customs union with countries that do not have similar agreements with Tanzania.
Kituyi said: "The best way to deal with the contradictions is to look at Tanzania acceding to Comesa again."
He told a press conference that Tanzania had said it would consider the matter.
Kenya, the biggest economy in the east Africa region, and a number of Comesa members have already established a free trade area (FTA) in Africa.
EAC and Comesa

Comesa members:
Angola, Burundi, Comoros, Democratic Republic of Congo, Djibouti, Egypt, Ethiopia, Eritrea, Kenya, Libya, Madagascar, Malawi, Mauritius, Rwanda, Seychelles, Sudan, Swaziland, Uganda Zambia, Zimbabwe

East African Community members:
Burundi, Kenya, Rwanda, Tanzania, Uganda

The FTA members have eliminated customs tariffs between them and are working on removing quantitative restrictions and other non-tariff barriers.
There are only seven members of Comesa - Angola, the Democratic Republic of Congo, Ethiopia, Eritrea, Seychelles, Swaziland and Uganda - outside the FTA.
Officials cite loss of revenues and competition from more advanced economies as reasons not to join.
Kituyi said Kenya would host a Comesa summit in mid-May and would encourage the remaining members to join the FTA.
The meeting will also discuss the finalisation of economic partnership agreements (EPA) that the European Union is trying to strike with African countries.
The EPAs are intended to replace the Cotonou agreement, arranged in 2000, that allows for preferential trade for goods from the African, Caribbean and Pacific countries to the EU.