Praise be to Allah.
If this money is given to the official, and it does not go to the coffers of the embassy, then it is a bribe and a haraam gift, and the official is taking it unlawfully and it is haraam for him. But if you cannot get the visa without paying this money to him, then there is nothing wrong with it, in sha Allaah, and the sin is on him.
The fuqaha’ made an exception from haraam bribes in the case of that which a person pays to get what is rightfully his, and in that case it is haraam to take it but not to give it.
Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) said:
If he gives him a gift to make him refrain from wronging him or so that he will give him his due, then this gift is haraam for the one who takes it, but it is permissible for the one who gives it to give it to him. The Prophet (peace and blessings of Allaah be upon him) said: “I give one of them a gift and he goes out holding it under his arm as if it is fire.” It was said: “Why do you give things to them?” He said: “They insist on asking me, and Allaah insists that I should not be stingy.”
From al-Fataawa al-Kubra, 4/174.
Taqiy al-Deen al-Subki (may Allaah have mercy on him) said:
What is meant by the (haraam) bribe that we have mentioned is that which is given to avoid paying one’s dues or to get something to which one is not entitled. But if a person gives it in order to get what is rightfully his, then the prohibition applies to the one who takes it. If the one who gives it cannot get his rights except by giving it, then it is permissible, but if he is able to get his rights without it, then it is not permissible. This is the ruling on what is given to obtain positions: it is haraam for the one who takes it in all cases, but with regard to the one who gives it, it depends on the situation, as we have mentioned.
Fataawa al-Subki, 1/204
For more information please see question no. 72268.
And Allaah knows best.