Tinubu gave the warning in his Democracy Day message entitled, ‘June 12: A milestone for democracy’ on Thursday.
The APC leader noted that many people fought for democracy and the June 12, 1993 elections changed the political climate in the country.
Tinubu also hailed the President Muhammadu Buhari-led administration for their fight against corruption and tolerance of constructive criticism.
“Nigerians deserve congratulations and commendation for their investment in democracy and for how far we have come.
“However, we equally must warn and remind ourselves how far we must go. We must continue to work to entrench and improve our democracy.
“We must continue to be vigilant and keep watch over our democracy and ward off those who may want to draw us back toward a dimmer period,” part of the statement read.