When someone is if Salat (prayer) and he finds that he has a desire to urinate he must stop the prayer and repeat it after urinating. But, when we have a little desire that will not disturb us should we stop the prayer? I found the Hadith that said that the man who is disturbed by the desire of urinating or passing wind his prayer will not be accepted. So I want to know at what pouf shall I stop the prayer? I'm a doubtful man and sometimes I think that I have a little desire that doesn't disturb me so I repeat the prayer.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Majority of Muslim scholars are of the opinion that starting to perform prayers while needing to answer the call of nature is dislikeable. The Prophet (Sallallahu Alaihi wa Sallam) said: "There is no prayer when the meal is presented nor when one needs to answer the call of nature" [Reported by Imam Muslim ].
The reason is clear that such a person cannot concentrate in his prayer and cannot perform it reverently if he is need to answer the call of nature.
The more one needs to answer this call the more his prayer becomes dislikeable; it even can become null according to some scholars.
Therefore, we advise you to attend the prayer after having completed Tahara (cleanness), aspiring to the prayer, being calm-hearted and leaving all other business. Doing so becomes more important in your case since you suffer from the doubts of urinating.
However, if you start the prayer and then feel a slight need to urinate, do not pay any attention to it and complete your prayer; there is no harm in this case.
Allah knows best.