The Red Bull driver was given a drive-through penalty as the move contravened guidelines introduced this season.
Alonso said: “It was dangerous for the nature of the circuit. It’s 300km/h and we were jumping on gravel. Not nice.”
Asked if the penalty was fair, Vettel said: “From my point of view, no, but it’s not for me to judge.”
Alonso went to the outside to try to pass the Red Bull and Vettel moved over, not leaving him a car’s width of space.
The Spaniard ended up with all four wheels on the grass but managed to control the Ferrari and get back onto the track.
He passed Vettel on the inside in the same place three laps later, before the German had been given his penalty.
Alonso said: “The race director makes the decision and they made one, but it didn’t change anything because [Vettel] was forced to retire.”
Asked whether there was enough respect between drivers, Alonso said: “I don’t know. Sometimes yes, sometimes no. It’s difficult for sure. It is in the borderline, this one.”
Alonso said: “Last year there was not a penalty, this year there has been. I think there is a big difference for the people who understand this movement.”
Red Bull team boss Christian Horner said he felt the penalty was “harsh”.