She was in Iran for President Hassan Rouhani's inauguration on Saturday when she found herself the centre of attention on the parliament floor.
Photos showed Ms Mogherini surrounded by a number of male MPs, taking photos.
Many social media users criticised the MPs, ridiculing them or labelling their actions "humiliating".
The Fars news agency posted a photo which many social media users felt showed Ms Mogherini unimpressed - and labelled the MPs' behaviour "strange".
Members of the Iranian parliament have found themselves under fire for "strange" behaviour involving the EU's top diplomat, Federica Mogherini.