Large Transport
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Human-Machine Interface
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Human Factors; Procedure
On approach into TFFR we received clearance direct AVSET. Captain entered it manually and flew direct. We were then cleared to altitude 3600 and also cleared for the RNAV 12 approach. The aircraft leveled at 3600 feet until the Flight Mode Annunciator displayed FINAL APP at which time the aircraft began to descend on its calculated profile which did not honor the altitude restriction at AVSET. ATC advised that we check our altitude and we climbed back up to 3600 and rearmed the approach.This event occurred due to the fact that when the AVSET direct was manually entered it did not include the restriction. The profile computed by the aircraft in FINAL APP was below this restriction. That fact that we were in VMC conditions possibly drew our attention to locating the field and reduced our verification process.Insuring that when a direct is received that if it contains an altitude restrict that it is entered and to ensure that in FINAL APP that the aircraft respects all restrictions. Better balance of attention between inside and outside the aircraft.
[Report narrative contained no additional information.]
Air carrier flight crew reported leaving cleared altitude earlier than ATC clearance allowed.