No action providing for any specific improvements or the appropriation or expenditure of any public money, except sums less than $3,000.00 for the appropriation,acquisition, sale or lease of real property; for the levying of any tax or assessment; for the granting of any franchise; for establishing or changing fire limits; or for the imposing of any penalty, shall be taken except by ordinance, provided, that such exceptions be observed as may be called for in cases where the council takes action in pursuance of a general law of the state.