Reading the news I sense that too but the evidence suggests otherwise.
I can't speak of Venezuela but Iran's sanctions were too long that Iran already found customers to sell oil to (including Europeans!). So in a way there is no need to sell any additional oil to Europe anymore. In fact if any sanctions were to be lifted, there is a good chance that mostly Russia oil reaches European markets through Iran.

Hint: A little more than 2 months ago Greece seized an Iranian oil tanker and Iran responded by seizing 2 US oil tankers. The Iranian tanker was actually carrying Russian oil and was heading towards Western Europe.