Dear Shailesh,
since you do not want to activate AVC on revenue items (which is quite normal), define a tolerance profile which will allow execeeding of the budget and assign this profile to revenue commitment items via derivation strategy. Follow the steps below:
SPRO>IMG>PSM>Funds Management>Budget Control Systems>Availability Control>Settings for Availability Control Ledger>Define Derivation Strategy for Tolerance Profiles
There create a derivation rule with Source field POTYP - Commitment iIem Category and Target Field as TOLPROF. Save the rule
Now check your entry again. I hope this will serve the purpose.